CONTRACT CANCELLATION

What a terrible experience I have with MTN since my contract expired in September last year.. I phoned them, sent emails and even went to the store to cancel my contract however it was never canceled and every time I follow up they tell me it's pending on the system and I should wait..from R500 per month to R900 for a contract that am no longer using and in december they debited me R1800... the whole thing happens while I have another 3 contracts with them which I am definately going to cancel without a doubt 😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡