Debiting my account without my permission

Nxatel has been debiting my account without my permission. This started in July and I went to the bank to reverse the money. Now it happened again on the 26 August 2015 at 01:16 PM. I ordered a phone last year and cancelled the order before they could deliver and now they debiting me. This time I decided not to go to the bank and resolve it with them. I have been communicating with them since last week Thursday and they telling me is that they working on it. they not telling how long it will take before I can get my money and its a big amount. This is inconveniencing me because I have other debts to pay. I cant make arrangements without knowing when am I getting my money back. I'm avoiding to go to the back to reverse it because come month end this will happen again. this is really frustrating on my side.