Vodacom accounts department billed me more than they should

I was due for an upgrade in July 2017, called in to cancel my contract with vodacom in September, asked for a settlement quote, which I paid in full. I then called in November to cancel my contract with Vodacom, but the upgrades agent offered me a special on a data contract, which would kick off on the 1st December 2017 (I regret agreeing to taking it). The data contract special offered to me included 10 gig day and 10 gig night data, quoted to me for R179 per month, plus a free router. Vodacom however, debited R1008 from my account on January 2nd 2018, and went on to debit R478.50 in February 2018. I called their accounts department to fix this, a lot of times, which was not fixed, I then reversed the funds, paid them what was due to them, but they terminated my line. I called their cancellation department to cancel this contract, but the pleaded with me not to close it and promised to look into the situation, they logged a third call through solutions, but this is still an issue. I'm very dissapointed with vodacom, I feel helpless.