On recent visits to Quest Diagnostics, they insist one must provide a credit card in order to have labs drawn. They provide a notice that it will be charged after insurance has been billed. I am concerned, because Quest always makes mistakes on billing. It's challenging to reach them and have them corrected. I anticipate even more problems if they have already billed the credit card. Especially because I have secondary and tertiary insurance. I called Discover card to see if there was anything I could do pre-empt this, but they were not much help. Any suggestions here?