Being double debited and told they cant do anythin

I took out a contract on 10/01/15 and was told I would need to pay a pro rata which was accepted. on the 15/02/15 I took out another contract and was told the same but with an added charge of sim and connection fee which was to be debited on the 20/02 which I budgeted for in feb. the fee went off my account and I then get a statement for this month to tell me I will be paying R901.61. I went to cell c Chatsworth where the contracts where taken out. they picked up I will pay pro rata for the new contract + the full amount and will pay for my older contract. this made sense however they added another sim and connection fee to bring the total to R901.61. head office was called and they stated it was not debited last month. I pulled out a statement but was told I need to print a 3 month statement which will need to be stamped and each page will cost me R17!! cellc will not be footing that bill and I was told to honor the debit this month and then give them the statement to open a case which may take a long time. I have not even budgeted for such a huge amount to go off and I need to pay over and above my mean to prove them wrong! I want answers since no-one seems to know whats going on