Bad service

I was a member of the gym .every month I paid my fees around the 27 th of each month via eft.but when I went to use the gym I was blocked for non payment because their debit order came off on the 1st of the month .they proceeded to unblock me so that I could gym and said they will accept my eft on the 27th The following month the exact same thing happened and again I was blocked for non payment even tho I paid via eft..again they unblocked me and said they will rectify it . The following month .again I paid via eft and when I went to gym..again I was blocked for non payment. I decided right there to cancel my contract due to the fact that I always got blocked for non payment..my contract was a month to month so I had given them a months notice for cancellation The gym contacted me and informed me that I owed 3 months gym fees because I had canceled which I think is ridiculous. It was a month to month and I cancelled because of their negligence not because I wasn't making payment..now I have been blacklisted because of their negligence or because they cannot manage payments correctly which I believe is totally unfair .I refuse to pay the 3 months for a month to month just because I canceled due to them