Product: Credit card or prepaid card

Type of dispute is I am being charged ( with compounded interest ) on an item I returned. See letter below and attached copies of documents explaining my dispute. 

I am writing because of a problem we are having with a PayPal order. We ordered an XXXX XXXX about XX/XX/XXXX, from a dealer named online, XXXX XXXX XXXX XXXX. Surprisingly, we did not receive a notice of shipment or even an invoice from them, and still have not. 
After waiting to be advised about our shipment for XXXX XXXX, we called XXXX XXXX number XXXX or XXXX times and left messages without response. We also sent an e-mail to XXXX, also without response. Finally, we decided this company might have closed. It was obviously having business problems because of having no live staff to answer or return our calls or e-mails. 
On XX/XX/XXXX, we received an e-mail from XXXX saying that we had sent a payment of {$190.00} USD to XXXX XXXX XXXX XXXX XXXX  XXXX XXXX We were led to believe that we had bought a XXXX  product from the XXXX company on their website, not some XXXX XXXX That PayPal e-mail included a Transaction ID XXXX and a non-identified Invoice ID XXXX. The Transaction document unbelievably acknowledged that the XXXX company was Non-US - Unverified, and that the seller hadnt given PayPal a projected shipping date yet. 
Since we could not make contact with this apparent XXXX front for the XXXX company and had no idea when, or if, it would be delivered, we looked for someplace else we could buy one. Still wanting the stand-up walker that XXXX manufactured XXXX we ordered the same model from XXXX on XX/XX/XXXX, as shown below. A few days later, this one was delivered, and we assembled it for use. 
XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX days after that, the box from the XXXX dealer in XXXX finally arrived! 
We immediately XXXX XXXX  requesting a return label and asking them to cancel the PayPal charge. After not receiving a Return Shipping Label and after their failing to answer several more of our phone calls over the next XXXX XXXX XXXX, we sent another e-mail on XX/XX/XXXX. Our email to them said that since you have not cancelled the order, we must return the unopened carton we received with your walker and contest this charge. ( Attachment A. ) My husband took the XXXX box to the local XXXX  office on XX/XX/XXXX and asked them to return the merchandise as a refused delivery. The XXXX  XXXX said he could not issue a new shipping receipt, because the box would have to be returned to the main XXXXXXXX XXXX XXXX XXXXXXXX to be assigned a new shipping number to prevent it from being redelivered to us, and that XXXX would then return it to the shippers address. Since that return was sent XX/XX/XXXX, before our XXXX return date of purchase on XX/XX/XXXX, we thought we had fulfilled our responsibility. 
BUT NO! 
Either XXXX never sent the return to the XXXX dealer ( unlikely ), or XXXX did send it, and XXXX never credited our account ( If we ever even had an account with them. After all, we still have not received an account number, a letter, or an e-mail from that company. ), or PayPal paid either XXXX XXXX XXXX XXXX XXXX XXXX XXXX seemed to have been owned by, XXXX XXXX XXXX XXXXXXXX XXXX XXXX XXXX, that we knew nothing about at that time ). Since PayPal evidently paid this XXXX - XXXX company for our returned order, they must accept their loss. 
Approximately XX/XX/XXXX, we received a hard-copy statement from PayPal, dated XX/XX/XXXX. However, we had still not received the product or a single response from XXXX, even after our calls and left messages inquiring about our shipment. 
On XX/XX/XXXX, we contacted XXXX by email to see if they had received the returned walker. They did answer this XXXX email and asked for our order number, which of course we had never received from them. We contacted them again on XX/XX/XXXX asking Have you received my returned XXXX XXXX walker back yet? And, Please cancel the charge on PayPal and bill me for the return shipping. No answer. 
Because of several conversations we had explaining the issue to PayPals Collection Department, they sent a letter on XX/XX/XXXX issuing a provisional credit and billing the amount back to the merchant ( Attachment B ). They said that the merchant had the option to provide supporting documentation within the next XXXX billing cycles that credit was not due. Those billing cycles have long since passed, and we have never been provided any such documentation. However, the calls kept coming demanding payment until another offer to investigate our dispute was received dated XX/XX/XXXX ( Attachent C ). This date is long past the XXXX billing cycles deadline. Still, the calls from PayPal/Synchrony keep coming every day. We decided to answer XXXX  of the calls and the agent said that a determination had been on the side of the merchant. Again, we have never received any documentation, or even heard about this decision. PayPals letter claimed thar you will receive a response via mail or email notifying you of the resolution of your dispute. This never happened! 
Consequently, since no documentation was provided to us ( the customer ) on this issue within the allotted XXXX billing cycles that the merchant had to respond and, since we do not have the product, and took every reasonable effort to return it to the merchant after it was eventually received too late and, since the merchant has not made a reasonable effort to conduct its business fully with the customer by : not providing a reliable means of communication, not supplying an invoice or bill of sale ( or even an order number ), not conducting business by answering its phone, or shipping its product in a timely manner, and since PayPal elected to enter into a business relationship with a Non-US Unverified company, they must accept the consequences. ( If PayPal would have vetted this company before taking them on as a vender, they may have avoided this problem. ) XXXX website now, as of XXXX of XXXX, shows XXXX XXXX XXXX XXXX XXXX XXXX, a different XXXX company. PayPal may not want to admit they sent the payment for Page XXXX our purchase to a risky foreign company from which they can not get their money back for our returned product. 
Our past two bills show a Past Due balance and the latest one, XX/XX/XXXX, shows an interest charge plus a {$40.00} Late Fee. We have had an XXXXXXXX XXXX credit score for XXXX XXXX XXXX are quite XXXX XXXX XXXX XXXX by this debacle. Can PayPal prove that the vender provided proper supporting documentation that will stand up in court before the XXXX XXXX XXXX XXXX XXXX Has the vender provided proof that they did not receive our return or made reasonably attempt to locate their box which was scheduled to be returned to them? 
We maintain that we owe no money on this issue, and if PayPals harassment continues, we will take whatever response is necessary to stop PayPals abuse. Therefore, as we have explained in many phone calls from PayPals collection department, they have no right to keep harassing us with phone calls and to keep up adding compounded interest on the original amount of a product that was returned. 
I am an XXXX XXXXXXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX. We have done our best to settle this matter, but to no avail. I am seeking your help because we are not able to pay for a product we do not have. 
I would appreciate your help if at all possible. Thank you for your assistance.