GYN office charges

Angie
Is anyone else's GYN telling you owe a fee that you need to pay because your insurance won't cover but won't provide a bill?
My office asks me every visit if I would like to make a payment; apparently there is a $660 balance that my insurance won't cover. However when I ask for a bill I'm told they don't provide one. This sounds crazy to me, I want to see what I'm being charged before I pay. After every visit I receive a bill for that visit of $30, however that's not getting applied to the $660- so I don't know what that $660 is for ???