OVERCHARGED DUE TO NEGLIGENCE

I bought a contract phone online on the 25th Feb 2015 and requested that they keep/port my number from another SP. A lady by the name of Julia called the following day and confirmed that everything including the porting is in order but after the delivery on the 4th of March 2015 they activated a new number instead of my old number, I called and requested them to cancel it and activate my number as per my request, I was told to buy a new contract sim card (R60) and email my ID and the sim copies of which I did and I was guaranteed that the other number was cancelled. It was sad to me when I found that a debit order of R598 went through my account and when I queried I was told the other contract still exists and I have call the cancellation dept. And I did but I was told I can't cancel, the contract is still new. I called Vodacom and spoke to a thousand of agents in different departments but none of them could help me up to today, they even suspended my lines and ruined my credit record. Anybody out there please assist me with this issue please...I'm so disappointed in Vodacom!