VODACOM BAD SERVICE

I went in to Vodacom in Bayside to buy some top-up data for my internet after a staff member of mine had downloaded movies and depleted the data. I was advised by the staff member (Surname Lombard) that I would need to buy 100G for the remaining two weeks, which I did. The end of the next month, I went to Table Bay Mall to pay my account. I queried the amount to pay, and was told that it was probably just the new month's amount added as well. I paid the approximate amount it should have been. The next month (end Nov), I was told that my Vodacom account was R5968.32. I asked the Vodacom staff member to clarify my account and was told that I would have to go to Bayside, where I bought the data. I went to Bayside to talk to the manager. I was informed that the staff member was no longer working there and had sold me 100G instead of 20G, which would have been enough. He had also marked it as recurring on my account, which means that I am now paying R1630.43 every single month. Vodacom is taking no responsibility for this and have told me that I have to pay the full amount, which has escalated to R5968.32, December not included. They have told me that they won't even look at the query until I pay up the total owing and also won't guarantee that I will be reimbursed for their mistake. My internet and phone has been cut off and I am at a loss of what to do. I don't have almost R6000 to pay.