Frustrated by the no reversals rule

Telkom has just took over R20000 from my account, we have never agreed upon this. Last month they took over R5000 but I let it slide because I had missed one or two months. They are always trying to debit money from me on different dates and I end up incurring charges. My frustration is that FNB is not allowing me to reverse my money, this is abusive and frustrating! I should have a right over My hard earned money, especially against ********!! I demand to be afforded the right to get my money bank. That other company needs to make an arrangement with me, this is *******! Period. I honestly need to change banks.