not canceling my contract

I have had the contract for over 2 years. 3 months ago I started to try and cancel the contract. Finaly got a customer care e-mail. Sent an e-mail on 25/5/2015 with my details and current phone number as I have never used the ones they gave me. Got a reply on 19/6/2015 saying that they don't have my number (after I explained that I don't even know the mtn numbers AND included my I'd number). I rep**** the same day and explained it again to them. Haven't received a reply after that and this month 1/7/2015 they AGAIN billed me on my account. Will not advise anyone to do business with them. I am very frustrated as either their phones magicaly doesn't work or they don't reply if you need to cancel your contract with them, but its ok if you get a bad pay record because they don't do their jobs.