Bad service - Cancellation

I had a membership with Virgin Active My ex finance signed to pay the account. We dont have contact anymore, no the account is in arrears. I have been at Virgin Active one evening only person that was helpful was the receptionist. I called the next day and spoke to the club manager she assured me that she will contact me back in 5 mins its been a week now. Still waiting for her call. I can’t understand how I can be held accountable for someone else bank account. I want to use my Vitality number to go to Planet Fitness but I get no assistance whatsoever from Virgin Active.