Your insurance from work is your primary carrier, and that is why the office billed them first. A discount plan is not insurance. Sorry that happened to you. Whenever you are having a costly procedure done, it’s a good idea to ask your insurance company how much will be covered in advance. I learned that lesson the hard way. My knee surgery was applied to my deductible, and I have to bear the entire cost myself. Now here I sit on disability, with very little income for several months, and I have a huge medical bill to pay.