******* deductions by mtn

I have been buying airtime from mtn and every time I load airtime, R49 is deducted. I forwarded an email inquiry and they indicated that it was subscription. This is a contract phone and I have never subscribed to any product. I have noticed that the number was used by someone else. The deductions are still continuing even if I told them to stop what ******* deductions and reimburse me for the three occasions. Their customer care sadly have not provided any assistance. I cannot wait for the contract to cease in in May.