Billed for service not requested

My husband's contract expired in December last year and they phoned him to inform him the contract will change, which was fine, we were happy with the changes they were going to make. The changes was just to change our current contract from a R269 for 5 GIG to a R99 for 1 GIG. We even told the callcentre agent that is 100%, but to our surprise they just added the R99 and 1 GIG to the previous contract. Contract was not changed and we are still paying for 5 GIG data which was not requested. After numerous visits and calls nothing has been done. They either keep you on hold when phoning the callcentre and after a while they disconnect you. I have numerous records of calls, emails etc and still nothing has been resolved. Every time we phone the callcentre to speak to the Manager, they put us on hold and after a while they just simply put the phone down. Now maybe by posting this we might get some response. The service at this stage are beyond pathetic. I need to get this resolved as soon as possible.