Health pay deductions

Each time I collect my chronic medication, the full cost of the medication is deducted from my Discovery bank account, and then I receive a claims statement saying that Discovery paid the provider. I did not give authorisation for Health pay to deduct money from my Discovery account. I can now not keep funds in my Discovery bank account as recovering the amount is impossible. Discovery has still not responded to my complaints. I would like to close my Discovery bank account please.