Doctor gave me the wrong information and i wanted to reverse payment

I went to a Doctor to do a root canal treatment and he advised me that it will only cost R1700.00 and some couple of rands for two treatment of which it will be done that day than i will have to return again after 5 days for the final treatment only at the price of R1700.00 and some couple of rands. To my surprise he now deducted twice from my Discovery saving account,called Discovery to reverse the payment but i was advised that it could not be done of which i fail to see why not cause at the end of the day its my savings.Anyway i will cancel the medical aid and i will advise other people not to take the medical aid with them.