*********** workers in the retentions department

I had two cellphone contracts with MTN. At the end of term I asked for it to be cancelled. I ended up with a R3000 bill. I just left it and paid them thinking you know what it’s fine atleast it’s cancelled. I had multiple conversations with so many agents and they said it was cancelled after asking. Now they coming with a R1900 bill!!!! They saying it’s cos I’m on a 0 rated contract. I didn’t want a contract ! I just wanted this contract to be cancelled and go on prepaid. How is it so difficult to understand. They said it was canceled so why am I getting charged !!! I need this sorted out immediately. The numbers is *** and ***