***** and negligence

I had 2 different contracts with MTN and one was paid up in 2020 and the 2nd cotract I paid it up in January 2022 and requested they cancel my contract. Today I get a call from DMC debt collectors advising that I owe MTN and that my contract is in areas and I was shocked as he'll as I knew that all my contracts are cancelled. I don't know how or why would I still have any existing contract with MTN as I received paid up letters .I need answers from MTN and if they never cancelled my contracts on their end they better make sure that they rectify that or my attorneys will be in contact because this is ***** !!!!!!