MTN is a ****

I app**** for a contract via online and the sim card was delivered but within 2 days i canceled the contract.i called and they sent me a ref number that my contact has been canceled..i was surprised the following month MTN debited on my account,i sent the message to MTN and they apologized that they will deal with the matter..they didn't..i am now blacklisted my name has been ruined for not paying the contract that i canceled last year..i want them to remove my name on the credit bureau..they must stop doing this to people