Vodacom *****s

I upgraded a data contract for the following deal: R149 for 3gigs and R270 for the laptop, they add up to R419.00 on the 19th of November 2015. I have a copy of a signed contract that states that the data must be capped, e-mail confirming it is a top up and are unable to go over the limit. Yesterday Vodacom deducted R7790 from my account and now the credit department wants proof of my deal. Customer services don't know how this happens, but now I have now salary and all my debit orders is reversing. How do you fight these people, my part of the contract is correct, and they are not prepare to do there part