South Shore Kia

I leased a new Kia *** and returned a 2020 Chevrolet Malibu. The Malibu was returned on September 28. They didn't return the car to Chevrolet until October 23, and now Chevrolet wants to bill me another month since the lease ended October 6. I've called the dealer over a dozen times to get this resolved to no avail. If you can help me with this, I'd appreciate it.