300% increase in installment and changing of contract by MTN without consent from client.

Years ago we took out a contract for 1gig data and paid R95, we seldom use this data, but kept it for emergencies. Then suddenly in August, they decided to charge us R185... September R405, Oktober R405... we phoned them and asked them to immediately cancel this contract and pay back the money they wrongly deducted from our account.... big surprise... November they again deducted R405. It is useless to try and phone them and if you go into the Mtn branch they just say a lot of people are complaining about the same thing but there is nothing they can do about it... Now Im just wondering... They deducted R1020 wrongly from me.... how many other clients have the same problem and how can we stop them from deducting any more money and how can we get our money back... without them giving you a 'credit'... I don't want a credit, I want my money back in my bank account !!!!!