cant get anything cancelled!!!

A few months ago one of my Mtn data contracts expired. So I decided to stop the contract. But one may not do it at a branch anymore you must phone in. This has given me stress to the point were I have become ill. I have spent around 2000+/- rand on phone calls trying to get it stoped but no one ever picks up there phone at cancellation's. The contract has also seemed to have increased in cost as well going from 199 to 299 a month. I am sure this is not allowed as I did not even get a phone call from mtn to tell me this and I did not sign any documentation allowing this continuation of the contract including an increase. I want this contract stoped now! Some one help!