Double billing of handsets

I would like to know why Vodacom has still not corrected my account, I am still being charged for two handsets. I constantly have to call them to follow up and then told the same thing, that the matter is still in progress..... How can it take more than 3 months to correct this error. In the mean time my bank account is being debited. Vodacom has pathetic service and I just want to cancel my contract. You are the worst service provider there is. Absolutely disgusted.