Incorrect Data Billing

In November 2014 my billed invoice was R12985.26. My normal monthly bills are between R800.00 and R900.00 per month. In October 2014 I received a sms saying that I had gone over by +-R1000.00 and that I should phone if there was a problem with my account. I left it as I could have gone over by R1000.00. However in November I did not receive any message, email or phone call notifying me that my cell phone bill was going sky high. When I spoke to the guy in accounts about this he said that's impossible, they would have notified me. He did also say that it does take a day or so to flag on their system, but this unusual data usage on my phone went on from the 22nd to the 30th of November(a full week) and no one informed me. When I queried this account when they tried to take the money off my bank account, I requested proof and an itemised bill of my data usage. Dinah Zimema sent me an excel spread sheet on the 9th of January, with no proof that it was actually my usage. I have sent numerous emails, phoned and gone in, yet not a single person has responded to my queries satisfactorily. It is now May and we still have not resolved this problem. Please resolve ASAP!