Product: Vehicle loan or lease

This is the letter I sent to both the dealer and Kia Financial which explains my problem. 
Attention General Manager or owner of XXXX XXXX  XX/XX/XXXX I am writing in regard to my purchase and lease turn bill from Saturday, XX/XX/XXXX. 
I would like to comment that I have been a long-time ( loyal ) customer for all our preventive maintenance needs on our XXXX Kia Sorento and our Lease from XXXX XXXX XXXX Sportage. I was also looking forward to purchasing the new XXXX remodeled Sorento next year. On Saturday, XX/XX/XXXX we test drove many cars after we were contacted by XXXXXXXX XXXX urging us, to come in and turn in our lease early and purchase or lease a new vehicle, before we came to the dealer we asked if we would be penalized on our last payment, we were told no our lease-end was XX/XX/XXXX, this would not be a problem. XXXX from Florida was our salesperson. 
After testing driving multiple vehicles, we decided on the XXXX XXXX. At the time XXXX  had stayed at home mandate in place due to Covid -19. No customers were allowed in the dealership. XXXX sat in the back of our vehicle and stated that our last payment would be waived if we wanted to pursue the purchase of the XXXX, he could make it happen. 
We also want to point out that our lease turn XXXX XXXX was almost XXXX miles under its allowed terms of the lease and was in immaculate condition and was garage kept upon turn in. 
All transactions were done on our cell phone, we spoke with finance as they picked the company with the terms we agreed to over the phone. During all this time there was no mention of KIA lease loyalty or we would be required to make the final payment on our lease. In fact, we were told to go home and wait for XXXX XXXX to clean and prep our new vehicle and they would deliver and pick up our lease later that afternoon at XXXX XXXX  hassle-free Covid safety delivery. We got our car and we were very excited. 
Unfortunately when I went to pick up our new plate and our lease plate the following Thursday Note I had to call and text if our plate was ready, XXXX didnt have any of our paperwork ready he just handed me two plates and told me I was all set. The paperwork would come in the mail. The paperwork has yet to come in fact when I got home and checked the plates XXXX gave us someone else plates from my lease turn in. I contact him immediately he did offer to come by and bring us our plate later that night. 
As time went on, I logged into my KIA account multiple times to see that my account to showed paid in full or closed this never happen. We tried to the KIA Finance there were no live agents Mid-XXXX due to Covid only a recording. 
On XX/XX/XXXX, we receive a letter from Kia Finance dated XX/XX/XXXX see attached. 79 days after purchasing our vehicle! We received a bill for {$810.00} Last Payment-Taxes-Turn In fee? I was in Shock Upon receiving this bill, we called Kia Finance and we were told it was our responsibility to deal with the dealer directly for the last payment being waived. 
The agent said even though we purchased a new vehicle it did not meet the terms for a loyal customer because we were not financed through KIA motors. We want to make clear XXXX pick our financing, not us nor was the fee of {$400.00} mentioned at any time. 
Left 5- messages with our salesman XXXX no return calls We attempted to contact XXXX XXXX talked to him once he said he would investigate it, never received a call back we left 8 more messages no return calls. 
We left multiple messages with XXXX XXXX ; no return calls always sent to voice mail. 
Left 3 messages with XXXX  XXXX  I finally started contacting XXXX XXXX XXXX Finally retuned my call after two emails and a two-voice mail. 
She put us in contact with XXXX XXXX at XXXX see email his response below. 
From : XXXX XXXX XXXX Sent : Monday, XX/XX/XXXX XXXX XXXX  To : ' Subject : RE : Lease bill Good afternoon, I looked into this matter of the last payment and it was not promised for us to make it. I looked at your signed WE OWE and also the signed worksheet. The disposition fee charged to you by Kia should be owed back to you from Kia motor finance. You did purchase a new Kia. I believe XXXX provided you with the phone number for Kia motor finance to get the disposition fee handled. 

Subject : Lease bill Importance : High XXXX, Thank you for your assistance in this matter. 

We filed a Complaint about XXXX with KIA Finance on XX/XX/XXXX Spoke with XXXX ID XXXX I called again KIA Finance on XX/XX/XXXX they were waiting for a letter from me to file a formal complaint spoke to XXXX IDXXXX I was told my complaint was closed on XX/XX/XXXX? 
Regardless of the outcome. My family will never purchase another Kia or will they have any future service done on our XXXX XXXX or XXXX XXXX or any vehicle at a XXXX dealer for anything! We will drive further and pay more regardless of all our future maintenance. It's my goal to provide the truth about our experience and the lies KIA has told my family. Hope {$810.00} was worth it. 
It's very disappointing to be treated like XXXX and not even get a call back from all the people I have contacted. I have exhausted a lot of time and effort in this matter to be blown off. 
You have lost a Loyal customer that can only speck negative about XXXX XXXX  and KIA Finance.