Taking money out of my bank account that doesnt apply to my bill

I do not know how this is happening.  for the past 6 months, I have noticed that Koodoo is withdrawing money from my bank account but it is not being applied to my account.  I have gone into the bank and they tried to stop the payment but it still going through.  Its different every month but is now starting to increast in amouts.  At first it was $30 or $40, now its $210…….  Can someone please help?