Incorrect billing

I have a Vodacom Fibre at home which I was paying R599 for but to my surprise in July they debited R829 I then called their customer care line to find out and I was told that they no longer have the whatsoever teriff plan that I chose before so they have moved me into the new and expensive one however I asked the lady to help me downgrade a bit and we agreed that I'm gonna take the R629 one but to my surprise in August they still debited R829 and today still I see that they just debited R829,, I just want my money back into my account that's all,, all these extra R200 that they keep on taking in the past few months.