Very Disappointed.

I have a data contract with Vodacom I normally pay R250.00 a month in the last three months its gone from R250.00 to R750.00 how is this possible? Last month Vodacom tried to debit my account with over R1000 lucky I stopped it in time. Do I need to cancel my debit order. Trying to phone Vodacom is a nightmare over a half an hour waiting and then you just get pushed back in the cue when no one wants to help you and top it all they same my account is behind but no one to help explain this.