Gym Company demands money from me.

I signed a month to month contract with them and which I’ll be paying 100 every month as long I go to gym.The first month I paid cash and I didn’t go to gym they ask me for my banking details so they can debit the money on my account, the second month I got injury I didn’t go to the gym and I call them that I cannot continue but they still debit the money and on that account the was no money... They kept debiting they couldn’t find money and then when I want to cancel with them they told me I should pay 1000 before cancellation.. I didn’t even step my fit in that gym they are saying am owing them. They force me to pay and they said is a month to month contract.