Debit order collection at any date they want to

I enrolled with them and never attended and I must pay even though I never used the service,I told them that I am not working and the money they require from me via debit order only of 1000 will see if I may have it every month end,wen money deposited in to my account they just debit anytime they want ,and on the 31 they went and debit my account,I cannot receive any money coz they are debiting ...I need them to return my money and since m not working I cannot to live like this.