I've never gotten a hold of a gym manager faster than when I reported them to my bank for fraudulently charging an account they said they'd removed from their system.
Before that I only went to small banks but they kept getting bought out by bigger ones every year my bank got bigger and bigger until I had a shit national bank again.
I've only been a member of two gyms, and they both let me out of my membership over the phone. One was 24hr Fitness in WA, and the other was some big chain in AZ (can't remember which one)