You hired the store to do one thing, teach you to scuba. Simply go to the store manager/owner and explain your experience. I dont know of too many owners that would like to be recieving that explanation, unless this particuliar instructor is the owner. In an time where the slightest of slights can send a customer to another avenue, a store just cannot afford to not know this story. I dont know you, but odds are your a customer that had a choice when visiting the store, a choice for spending your money with them and now another choice that you didnt subscribe to. Women aren't going away anytime in our lifetime, if there was a gender issue with you, there was probably one before you and will be after you. You can reasonably expect to be taught scuba, whether its how to use the tables, fit a mask or clear a mask, if you cannot get that, there is something terribly wrong with that situation which it'll be your choice whether to continue to support the store.