I don't think you were supposed to do something else in hindsight? They billed your insurance correctly.. because of your HDHP, you owe the ~$600.

I have never had this issue with literally any other providers. I give them my insurance info, I get a bill a few weeks later, bill gets paid. I don't understand how, over the course of the year, they couldn't bill on time and give me a proper bill every once in a while, instead of playing the scumbag card and not sending anything to the insurance until after we had finished. That's what feels like happened.

When you told them you had a HDHP, that doesn't mean they ask you to pay more than $25 upfront. They have no idea if you've met your deductible.. They're going to attempt to bill them.

I expect them to bill the insurance and present me with an actual bill every once in a while, not lumping it all together and "SURPRISE HERE'S YOUR FINAL BILL" 6 months later.

If you can't pay the lump sum, you can contact the hospital/office and setup a payment plan.

I intend to.