tough one, the sale of goods act says you have reasonable time to make claim against the dealer, but i'm sure the responsibility must lie with the dealer to make sure the bike is all ok.. i would try asking for your money back and then the Citizens Advice Bureau if nothing comes of it.. but you may have to fight it through a solicitor which may be costly..
you could try HPI, if it has been written off and did not show on the report you should be entitled to claim off them, but as usual check the terms and conditions
the problem you may have is proving all these defects were there when you bought it
