I think I have a better plan.
I used to manage a health care billing office. Believe me if you pay and then the account rep gets a check from the insurance carrier they are very likely to not worry taking the correct adjustments (assuming they are contracted with the insurance) this can mean a headache for you. <br>
If you want to do this, don't pay at time of service. Let the provider send the bill to the insurance company wait a month and then start checking with the insurance company when they pay the bill, verify they "covered" then entire amount. Then call the provider and pay with the credit card. Thus you should have to wait significantly less time for the check and take a smaller chance on an account rep making your life miserable.<br>
(don't know anything about legalities, most times provider will send you a statment that you are not supposed to pay, but says at the bottom "pay this amount" therefore i can't see any legal problems there)