Let the shipping company know that making you happy should be their number one priority. You have the sympathetic ear of thousands of biking enthusiasts on this forum. Threaten them with exposing their name to this community. A bad reputation is exhorbitantly more expensive than replacing a frame that they clearly damaged. Additionally, a good reputation is way more valuable than the frame.

Another option is to sue them. Forget about their policy about accepting a package before realizing the damage. The shpping company would find it cheaper to just replace the frame than fight a court battle.

I hate to see this shipping company take advantage of you this way, especially since the shipment was insured and there is clearly damaged packaging. Somebody has dodged a bullet at your expense - don't lay down and just take it.