we continue to be charged for maintenance costs even though we have stopped using our timeshare over ten years now.

Hi, I had a time share week in the USA, which back in 2018 or before, we contacted the company and asked to relinquish our week as we didn’t use it, I had no paperwork from them so I presumed it was all sorted, earlier this year I started to get invoices from the company for back fees, I emailed, tried to call then, sent recorded letters and no correspondence other than repeated invoices, I kept trying to email to ask why no bills for 4 years etc, Today I received a letter from a debt collection agency in the USA for the fees, Where do I stand? I only have the recent correspondence as not hearing from them for years, during covid I cleared out all the previous paperwork as thought it was all sorted and I no longer had the week. Any advice or guidance would be appreciated. Many thanks