Charging me for a contract I have not signed

I do not have a signed contract however Planet Fitness is still charging me every month. I have been calling customer sevice but every time they say that they are waiting for head office to send my contract details. THIS HAS BEEN GOING ON FOR 3 MONTHS. I have sent proof that my contract has not been signed, however I have had no response back and am preparing myself for another charge at the end of the month.