Was the cancellation form in the bottom of a locked filing cabinet stuck in a disused lavatory with a sign on the door saying "Beware of The Leopard"? :)
If you look into the ownership of major gym chains you'll find that they are owned by financial companies - more specifically billing companies.
It seems like providing the gym itself is more of a side hobby to the main business: find people to bill and keep billing them whether they like it or not, and build a core competence to avoid ever not billing someone.
How can the gyms get away with this?