Dealing with the employees mistake

I called the call centre to cancel a a black tag and a freeze my account since I wasn't getting a chance to go to gym. Next thing I know is, I owe the company 7000 when I wanted to go back to the gym. They keep on telling me that I should pay wat i owe, whose fault was it for them to not do freeze the account and if I owed them why didn't they deduct the amount and had to wait till its this amount to pay back, nothing changed I still have the same account number and on top of that I had a debit order for them.