Photos Being Taken In Women's Locker Room At Gym

I've notified management and front dest operators three times now regarding photos being taken in the women's locker room at the gym. One of the gyms group exercise instructors are taking photos. This morning a young girl walked in with a tripod with phone attached and ready to record !! When I let them know photos and filming are not allowed they want to argue about everybody's doing it. For all I know they could be selling these pics of women draped in their towels or naked at online sites.

I am ready to file charges. What is the process, thank you for your help.