Complaint regarding the use of incorrect bank account

Have been trying to change my bank details only to find out 2 months later that they do not have an agreement with the bank that I am changing to, so they reverted to my old bank account, which is no longer in use without advising me and unpaid bank fees have been levied. I receive calls more than once a day to pay my premium but not one person reads my correspondence first so that they can assist. I have even sent an email to their CEOescalations mailbox with no response. I have advised them time and time again that I do not have an alternative bank account. I was advised that they will debit the same unused account at month end. I have been refusing to pay my premium until this has been sorted out.