Unable to cancel contract

Beginning June 2015 we informed in writing Planet Fitness after 2 years that we are terminating my son's contract. Besides not responding to my e-mails, they continued deducting for July and August. Although I cancelled both d/o's Planet Fitness eventually confirmed in writing that the contract has been cancelled, but that I still owe July's membership fees. Although I have requested proof of why as we have timeously cancelled the contract, I have not received any feedback to date. Although the initial contract was from 1 June 2013, my son was only to start working out at the gym from middle July as renovations was not finished on time. No discount was ever offered. I will most definitely never ever advise anyone to join Planet Fitness