Taking a step back, what type of gym only opens at 9 AM? It is reasonable to assume that a lot of members sign up to work out either before work or after it, and generally you would assume the working day to be something along the lines of 9-5 or 9-6. So not being open an adequate amount of time either side of that window is not reasonable for an establishment in that industry. If they want to do that fine, but all existing members should be asked if that's ok with them, and if not then refunded a pro-rata amount of their fees.