Body Lab review: Complaining about the gym

I was scammed by agents of Bodylab gym in Kempton park. They forced me into signing a form to join the gym with the pretence that its a free month trial then if I'm interested I will pay the first instalment for my membership to be activated and if I dont want to join then it will automatically be cancelled. Since February I never set foot in that gym and now they demanding I pay 30%of the whole years installment to cancel