MTN failure to cancel contract

I had a phone contract and had attempted to cancel this contract during the time of 2004 and 2011. Between 2004 and 2011 I had personally gone on multiple occasions to MTN and during that time they assured me that my contract would have been cancelled yet my debit orders were still deducted. I had attempted to cancel this number 3 times and till now the debit orders are still being deducted. I am not always in the country and cannot constantly have to come back to sort this out. I would like this problem to be sorted as soon as possible. The number of the contract is, ********** 801