Metrofibre overcharge

Been a client for few years. Last year I get a call asking if I want to add more mps to my current wifi for speed etc and sure thing my installment changed from R400 to R450. I was fine with it. January comes I am charged R499 now I email them and asked them to advise why is it changed and meanwhile someone decided for themselves I needed 15mps? Charging me without my consent? I then asked that they change it back to R450 so then this month I am charged again for the exact same amount x2 because they didn't deduct properly last year. I been sending emails and as calling is useless to say the least. I had to drive there before to resolve matters of wrong chargers.

Can someone help me please. The actual wifi is Great and we get good connections and all but this is now not fair to be ignored and matters not being resolved.

Claudette