Did your ad specifically state $350-500? When were they upselling you to $700- on the phone or when they showed up?
Next time, use an agency to ensure consistant pricing and to avoid flakes. Most agencies will only charge you a $50 booking fee for a bj plus the girl's rate.
_________________________
"What I do know is that if Karen Carpenter and Mama Cass Elliot had shared that sandwich they'd both be alive today." -Michael K