Very angry client

I have been trying to change my banking details for the last month now and they still refuse to stop debiting the wrong account, which is costing me money as the debit order keeps bouncing. Customer services have been useless thus far. I filled out a form at the actual gym on the 3rd of september to try to ensure that the bank account was changed by now. then they debited the wrong account with my daughter's membership and I tried calling them and they assured me that the banking details had been changed for both mine and my daughter's account. they are supposed to be redebitting my account today for my daughter's membership, but yesterday they ran the debit for my membership and it went through the wrong account again. I purposely emptied that account as I don't want any debit orders going off that account, so they will never get their money if they don't start debiting the correct account, but I cannot keep nagging and begging for them to debit the correct account when I have already been trying to sort it out for a month. I am so sick of dealing with them and now I think they are flagging my calls as I end up stuck on hold for ages. the customer support after the sale is made is absolutely shocking. I WILL be cancelling my, and my daughter's, memberships as soon as the contracts expire. I am so angry that I have no interest in repairing the relationship anymore.