No Response (im apparently owing money

I cancelled my membership in July 2014 and when i went to apply for a new membership about 2 months ago i get told that i cant apply until i paid outstanding membership fee. as far as i am aware my membership was paid in full so i told the agent(che) to go back and double check as im not owing anything but he does not get back to me and about a month later i get a letter from a collections agency, i try calling them but get transferred from one person to another with no help. i then call planet fitness call center and they say they will look into it but again no response then i get a mail saying query closed and again i call the call center and no assistance. on the 20th November i sent a mail to the call center and till today no response. what do i do next. i think this is really a waste of time that i have to complain on here but what choice do i have. Hopefully ill get a response <br> Call center ref number PF***