MTN and MTN Insurance billing

So I had a contract with mtn which they was successfully cancelled last year. Fast forward 10 months and I'm being called by debt collectors. When I go to MTN I am being sent to mtn insurance company, when I go to the insurance company they say because I was not a debit customer I need to take it up with MTN. MTN and MTN insurance are both not taking responsibility and my credit record is being wrecked in the process (according to VVM). Also is insurance not supposed to lapse after 1 - 3 months?