Virgin Active South Africa is ****!!!

My 2-year contract expired over a year ago and was then moved to a month-to-month contract. I then changed banking details where my account was being debited, and informed my branch of my change, so that they could debit the new bank account. This was never done and they kept debiting the old bank account. Now VA is telling me that my account is in arrears. Firstly, to what extent do the arrears get on a month-to-month contract, especially when collection is not successful? Why am I at fault when it was your staff that did not update my details when I diligently requested the update in January 2023? I will not be paying this and will be canceling my membership.