billing

On the 20th of January I paid a settlement amount of R5302 to Cell to settle my account, I asked them to change my number to pay as you go. That settlement amount I was quoted by them. I called the next day to confirm if they received the amount and they told me it does reflect and they will continue with my request. I even received a sms to confirm that my number is now a pay as you go. On Friday the 19th I called again to find out if everything was still in order. The consultant again confirmed. To my surprise when I woke up on Sunday CellC has debited me with the same amount I paid last month. I confirmed with them more than once . Now my bank account is overdrawn and I'm still waiting for my other debit orders to go through. I called them again this morning 21st Feb to query that and they are telling me that it's going to take 48hrs to resolve the query. Who is going to pay for the bank charges if the bank return all my debit orders, do they know how much inconvenience they are causing me.