I had a two year experience with cell c which ended last year 2024 October

I had a two year experience with cell c which ended last year 2024 October.I wrote a letter requesting they close my account since the contract has ended.But after sometime they started sending bill and terminated my line,went to their shop a few times trying to solve the problem to no success and I paid R1800 in (June2025) of which I knew nothing about.Again in July 2025 I have just received a message saying I am owing R395.15 whereas I called them to close off the line and I have been requesting the letter of completion and they are not giving it to me. Please help