Bad customer service

Good day. I'm currently a member of the escape gym for the past +-6 months. I have been making my payments via debit order and I recently changed my banking account and I made it my duty to notify my debit order for escape gym at approximately 14 days before my debit order went out. I spoke to an Indian lady from the accounts department and she assisted me via the phone and she took all my banking details down and said that it's been updated I've also given her my new contact number. As far as I was aware about my account with the escape gym it was up to date. I called in today to check up on that because I was on my way to deposit some cash into my old account and when I saw my balance it was on a negative balance and I was shocked so I printed out a bank statement and enquired about this. My bank charge is sitting on R 815.00 at the moment because of this unpaid debit and I will not be liable to pay up this and then also be liable for paying an amount of R650 something towards the escape gym for my membership. I've called the escape gym 4 times I spoke to a zandile at first she made it seemed as if I was lying about this and when I asked for the manager I was told that she wasn't in. I called back for the second time and I spoke to Derrick because I signed up for the membership with him. I was help by him and I was referred to speak to the manager and I was put through by him and the call automatically cut off. I then called back and asked the receptionist for details to lay a complaint about the situation I'm in and I was just transfered to the manager of the gym who magically was in then and I spoke to her and she offered me to pay R500 and something which was unreasonable and I would like to know who's going to be liable for all this because I made it my duty to notify you guys way more then 10 days. As a customer I expect to be notified of the outcome of this situation urgently. I want my membership to be canceled because of you guys incompetence towards my situation I'm currently in because of your staff. Also the Indian lady I spoke to over the phone should be liable for the expenses I've incurred.