Product: Vehicle loan or lease

We turned our leased vehicle in after 36 months of paying every single payment on time. It was returned at the start of the pandemic so we literally dropped the vehicle off without receiving an inspection or opportunity to discuss it's value or any equity it might have. We turned it in in good condition with below average mileage. We were told we would be hearing from someone. That was XX/XX/XXXX. Several months later we received a bill for a turn-in fee. At that time I emailed HMF to see if that fee could be waived, I was not making my full salary due to the pandemic. NO RESPONSE. I reached out a second time, saying this is my second attempt to reach you regarding this matter, NO RESPONSE. My turn-in fee was sent for collection, with no regard to my email or an opportunity to pay before being sent to collection. I called and was told I could make payments to satisfy the debt was never told it would seriously impact my credit. The terms of the lease have been satisfied and debt paid. I learned about the impact it had on my credit while trying to refinance my mortgage. My score was low and nothing in my history had changed. When I researched it I found it was due to a derogatory mark on my credit from HMF. I have called many times, spoken to many agents to no avail. I have disputed it through experian and it was resolved but still reflecting on XXXX and XXXX. I did not know I'd have to dispute it across the board. I went into my dealership and the GM  was on the phone with another customer with the same issue. The GM gave us the number of customer service and I have been in contact with them but getting nowhere. I was told by one agent, XXXX, it was all resolved and would be reflected on our credit XX/XX/XXXX but nothing had changed. I called again and was forwarded to an " account specialist '' XXXX who actually sounded as if she cared and was going to email someone to help get this resolved. My lender reached out and was told they don't discuss with third party companies that we would have to call ... .which I have more times than you can possible imagine. I received an email on XX/XX/XXXX saying they'd been trying to reach me at a number nowhere close to any number I would have provided and that my case was important please send new number, which I did and now 4 days later still no call or return email. I was told my the GM that the reasons my emails were not returned was because of the Pandemic, " no one was working '' so as a result I'm penalized and a negative mark in now making my credit score lower than what I need to get a good rate with no closing costs on our refinance. We were supposed to close in XXXX, now XX/XX/XXXX our 60 day lock expires and rates have since gone up. I need resolution and I need it now, this is beyond ridiculous. The customer service department is a joke. This could have and should have been resolved by now. For the number of times I called and the amount of time I have spent on hold, being transferred, and the number of agents I have spoke to should have been ample to resolve this issue but you can never speak to the same agent and your lucky if you get the same department. I have tried to reach customer service again today and get a maintenance message and then disconnected. My husband and I work very hard, we are good citizens that pay our bills, this blemish on our credit and the battle we have had trying to get it corrected is nightmare. Any help you can offer will be greatly appreciated.