Angry, disappointed, hurt and confused customer

MTN has charged me for a number in which I do not posses. I sent several email and call MTN to rectify my invoice for the past 4 weeks with no luck. I have recently went to their branch and was told I own R5 500 which means that they have not fixed their blunt and expect me to pay for it. MTN has suspended my service on the two accounts in which I do have yet they expect me to pay for the three numbers. I contact NCR and Consumer Rights in which their was no assistance. MTN South is acting like Goliath and which I cannot be David.