Only cover $10,000

[avargas 2]

So I got approved, but getting the run around now. Originally I was told my insurance would only cover $10,000 toward the surgeon who does my Gastric Sleeve surgery and I would have to pay the surgeon anything above $10,000, but hospital would be covered. Did all my testing had date set and Now they are saying the will only cover $10,000 total for the whole surgery and I have to pay everything over $10,000. Which the hospital is telling me it will be about $27,000. Any ideas if there is anyway to get my insurance to pay more than $10,000? I don't have an extra $20,000 laying around.