My last input on this one..wall and head come to mind
I would take pictures of the damaged frame especially around the headstock. Go then and see the dealer, bearing in mind anything he sells for the road must have a minimum of 3 months warranty( they often say no warranty but are obliged legally to provide 3 and they know it)
Show the dealer the damage and point out frame straightening or not NOTHING will ever get that bike back on the road legally even more so considering the cracked frame around the headstock.
Then having established the bike is a dead one ask him what he intends to do about it? He inevitably will ask you what you want to do about it. Given the state of the bike and his lack of pdi which would of spotted this a country mile off assuming he is honest I would strongly suggest that you ask him for your money back in full and then ask him to van pick the bike up.
If he fails to do so then first port of call would be the police in regards to a cat a or b bike being placed on the road, then the trading standards as to unfit for purpose, then the dot inregards to pdi failure then of course the small claims court to lodge a case for the return of your bike funds, the cost of the smalls claims process and any other funds lost i.e. insurance cancellation, tax loss on road tax etc
Beyond what you have been offered in advice so far paddy I doubt anyone can offer any more
If you feel the issue is you confronting the dealer then either someone you trust or feel that they would support you should go with you also?
Good luck and let us know what actually happens next