Telkom keep deducting money

Telkom is the worse company I've ever dealt with. The service is terrible. Account dep doesn't know what's going on there. I've never been behind with payment. Always up to date. Since last month they've around the 15th they've been deducting R796, 2months installments from my account, when I phoned they told me they didn't pick up the payment for April, i've emailed proof of payment to them, they said they will rectify it and pay me back. Now this month the same happened. When you phone and want to speak to a manager they won't let you. Obviously there's a mistake on their side they not rectifying, every time it cost me my time and energy always the same results. All I'm asking is for the problem to be sorted now!!!!!