Gym Company is Bull****hing me

I'm getting really frustrated right now by these people the Gym Company. Sometime last year they said I was in arrears whereas my debit order was running every month. Without my consent they started debiting double on my account when I asked they said I must come with statements. I did that all of sudden was told that they have been getting money ony 1 month is missing. They continued to debit extra in December last year I did not say anything and now they are debiting extra again, what the f*** are they doing? I'm annoyed I regret joining that gym. I want f**n answers. Or I want to cancel the **** membership nx!