Planet Fitness Over Charged for cancelled memebership San Antonio, Texas

I cancelled my membership verbally with a representative present at the center after a workout. I asked her if there was anything I needed to sign to void my membership. She told me that she would cancel my membership herself. So I left the fitness center believing my membership would be cancelled and no charges would continue. They still charged me for 4 months. Later I asked them why they were still charging me? Their response was that I was suppose to sign a document or write a letter stating my request for membership cancellation and mail it to some address. The representative NEVER mentioned anything about signing a document or mailing a letter to cancel my membership accordingly.

I was wondering how many other members were lied to and scammed in this manner.