*****!!!!! THIEVING MTN!!!!!

I have a contact with mtn, the billed amount is R580.25 In December I was billed R1039.75 This is according to their customer care is a usage limit which was increased and out of bundle data that was used. But no such increase was made, also I was out of the country during this billing period and was using a foreign SIM card. So no data could have been used anyway. Today I received my December bill and the amount is exactly the same again. This is *****. I have signed a contract to pay R580.25 per month. I will stop my debit order if this is not resolved by the end of the month