Virgin Active accounts is not within the law

How can Virgin active hold me liable for my fathers debt? I was 15 at the time that my ****her got me a gym contract. Spoke to the head office today and they said i must pay my fathers debt because he was responsible for the account. Surely there is a law against that . Ref*** I wanted to open my own gym contract but looks like they do not want my money? Me and my girlfriend wanted to join.