Product: Vehicle loan or lease

My complaint is with the company GM Financial, regarding my auto lease. Here is rundown of my issue : -On XX/XX/21, I paid off my lease with a full lump sum payment of $ {$4600.00}. After this payment posted, I checked my account on GM Financial and saw that I had a {$0.00} balance and that I had 0 payments left on my lease. My assumption was that no more payments would be taken from my bank account. 
-On XX/XX/21, a regular monthly payment for my car lease of {$330.00} was still taken from my bank account. I checked my account and noticed that my auto-payment was still active which caused the monthly payment to still pull. I de-activated the auto-payment at this time. 
- After this XX/XX/21 payment of {$330.00} posted, I checked my account and noticed that the account did not reflect this extra payment. My account still showed {$0.00} balance and 0 payments, instead of - {$330.00} balance. 
-On XX/XX/21, I tried calling GM Financial about this issue, however their phone lines were always busy. I attempted 3 phone calls, each one I was waiting more than 20 minutes and no one answered. 
-On the same day, I started a chat conversation with GM Financial about this issue. I chatted with someone name XXXX, she said she was reviewing my account and then she never responded again. 
-Same day, I chatted with someone name XXXX . I brought up the issue, and XXXX told me that the payment was cancelled and that I should see the refund in my account the next day. This was incorrect information -I did not see a refund on my account on the next day ( XX/XX/21 ) so I chatted again with GM Financial , this time with someone named XXXX XXXX She said that the refund was not processed yet by XXXX the previous day. She said she would process the refund that day and that it should take a couple weeks, since the payment would need to post and a check would need to be issued out. I gave the go ahead for this process to happen. This too was incorrect information, as I found out later that this refund was never processed at this time. I asked for a confirmation number to be provided for this refund, but was told that GM Financial does not provided confirmation numbers. 
-On XX/XX/21, I chatted again with GM Financial XXXX asking for the status of my refund. I chatted with someone named XXXX. She informed me that a refund was processed as of XX/XX/21. Once again, this was incorrect information. 
-On XX/XX/21, I chatted with GM Financial again, this time with someone named XXXX . Once I asked for the status of my refund, XXXX never responded to me and I exited the conversation - Sameday on XX/XX/21, I chatted again with someone name XXXX who confirmed that a refund was processed on XX/XX/21 and a check would be mailed out. This was also incorrect information. 
-On XX/XX/21, I chatted again with GM Financial , this time with someone name XXXX XXXX XXXX informed me that a refund was NEVER requested and that the XX/XX/21 payment of {$330.00} was still on my account. XXXX told me she would request a refund at that time. I once again asked for a confirmation number, and was told that GM Financial does not provided confirmation numbers. I asked for the payment to be refunded to me via ACH payment, but was told that GM Financial only sends out physical checks. 


It is now XX/XX/21, and I have still not received a check for my refund payment. Here are my main concerns with GM Financial : -Their system allows for the pulling of payments when account balances are at {$0.00}. This seems like a huge issue. Any financial record keeping system should easily be programmed to not pull any payment on an account balance that has {$0.00}. 
-Even after an extra payment was pulled, my account never reflected this extra payment. My account showed no trace at all of an extra payment being applied to it. 
-The customer service representatives either gave incorrect information to me, or never processed the one thing I had asked them several times to do. 
-GM Financial does not provide confirmation numbers for any of the functions they perform. This seems very odd to me. 
-GM Financial only sends physical paper checks, and no ACH payments. This is also odd to me. I have worked in XXXX for 13 years and confirmation numbers and ACH payments are something that I have personally handled every day. I worry that GM Financial simply won't do these things, instead of can't do these things.