Cancelling gym membership after retrenchment

Please if you can help me get out of my gym membership with these people. I’ve been going back and forth with them since July. I sent them my retrenchment and cancellation letter, however no one is attending to my request as the debit order went off again this morning. I cannot afford to be worrying about gym membership when I might not have a roof over my head after losing my job in July, please if someone can assist me put this nightmare contract to rest!