INCORRECT BILLING

in April 2015 I upgraded my contract with MTN since then my billing was incorrect - i phoned several times to complain but no one seems to be able to get back to me - i need a copy of my contract where I agreed to pay R430 per month but every month my bill came to much more than that. I had to cancel my debit order at the bank not for MTN to debit my account anymore as they were deducting more than R1000.00 per month - no one seem to be able to sort my account out - im sitting with hundreds of reference numbers and names of people but no one comes back to me. My account is now suspended due to the fact that I cancelled my debit order but still no reply from MTN!!! what do I need to do for someone to come back to me???WHAT DO I NEED TO DO???