i was blacklisted

my ex boyfriend open the gym account for me in 2013 which i didn't attend because I'm working long hours I ask him to cancel he didn't cancel he was the one whos paying the gym i receive a letter from the gym saying i was blacklisted i went to them with the letter an told them i didnt open any gym my ex did so how come i receive a letter that im blacklisted they told me to tell my ex to pay but they have all his details i didn't sign anywhere i didnt apply for a gym but now im blacklisted please assist me to clear my name .