Unhappy with service and want to opt out

I recently joined Flexi club with the hope that they gonna help me with my bookings so when I tried to make a booking in February for December they told me they are fully booked whereas I was told that I could make a booking anytime I wish so I called them and told them I want to opt out of the contract I was unable to do so please help as its not working for me since I pay a lot if money.