Still deducting for cancelled contract

<p> I cancelled my contract for a data line in March 2016 which was to have last debit order in April 2016. To my suprise Cell C deducted for the same cancelled contract in May and June. I called them to cancel the whole thing and refund me but never got a call back and resorted to reversing the debit orders. </p> <p> </p> <p>I need Cell C to stop trying to debit my account as i received notification of an attempt to debit my account today - or ELSE THEY MUST CANCEL MY EXISTING CONTRSCT BECAUSE IF I UPGRADED MY CONTRACT, WHY WOULD I HAVE TAKE A NEW DATA LINE. iM EXTREMELY ANGRY !!!</p>