Can my dentist bill me for a crown that has not be placed in my mouth and won't bill Gov. secondary insurance?

I had a root canal done 3 weeks ago and before having it done, I let them know of a primary insurance running out and my secondary goverment insurance. They billed my primary insurance for the crown and now telling me I owe them for a crown that has not been placed in my mouth. They are refusing to send into goverment insurance because it needs approval and they already made the crown. They told me that they would reimburse me when they get paid from goverment. I told them no and have not paid. They knew my situation. Can they do this?