Incorrect billing

After 18 months of a two year contract I noticed in my itemised bill unusual charges. My 18 month history showed short, inexpensive calls to my children but now I could see that all calls in the month to my teenage children were for long periods of time and very expensive. I know I never ever have long mobile calls with my children. Then I found strange sms costs at over r10 per text message. The bills weren't making sense. In total I received 3 bills like this until they returned to 'normal'. Due to these errors I felt I couldn't reclaim my works call costs (knowing that inconsistencies lay on my account). I queryied my call charges and itemized bill with Altech autopage through 3 phone calls to customer service and 3 trips to the centurion shop in person. No one actioned my queries whatsoever. Eventually I took a day off work and went to the offices in Midrand. Eventually I managed to get a manager to look at the account and he confirmed that something appeared irregular and that an investigation would be opened. He also acknowledged I would be refunded. After 6 months Altech autopage came back saying 'nothing is wrong'. I have been ****** and cheated!!