In Debt for life, no real way out

I joined in 2014 and after signing my contract I cancelled in writting on an e-mail three days later without ever entering the gym once. Not only have they still not cancelled my contract they still send threating e-mails bills and sometime try re-instate the debit order's. My daughter's son has the same problem after cancelling in 2011 they won't leave him alone. Do not sign a contract you will be in Debt with them for life and there is no way out. I have gone to the top and have still had no joy!