Extremely unhelpful regarding billing mistake

Autopage in Warmbaths switched my account with someone else's and following that I got a data account of more than R12000. Most of the data was used at times such as 01:00 am and seeing as I am a 62 year old lady I am asleep at that time and will definitely not be using up to R1000s data at a time. After numerous phone calls, e-mails and even a visit to head office the problem has still not been dealt with and they are in fact threatening legal action. I have never come across anyone as unhelpful as the Autopage employees and regardless of which department I contact, nothing is being done about this situation.