Sam
Rule of thumb, you NEVER turn down a request to dance - Unless you have a bad foot/ankle or you don't have your dance shoes on. It's just considered plain rude. Besides a dance is all of what 2 or 3 mins?
The ONLY way to get better is to get out there on the dance floor and DANCE. OK maybe you don't feel like a gold level student. NO ONE does when they start out. Everyone makes mistakes - you just laugh about it and go on. If you partner knows a step you don't AND you want to know about it, ask her to show you.
Acting flaky on the side lines will keep all the girls from asking you to dance.
If this place is not up to par with your personal standards, run out the money you paid in and find a new studio.