Ah Evans and Cannondale, yes I've had this recently, I have now given up as it is too much stress, but Evans have lost me, all my colleagues and all my mates as customers, that is significantly more value than my bike.
They were rude, barefaced lied to me about mechanical systems (sadly for them they chose a chartered mechanical engineer to lie to, with a witness (always take one, and maybe a tape recorder when having these discussions, and write it down as soon as you get out of the shop)) and took forever to sort it out, which they haven't to my satisfaction, but have now done the legal minimum.
Whilst the bike was with them the chainring guard got bent, and the mudguards got bent. Not a big hassle, just more evidence of their lack of professionalism and general big company versus small customer mentality.
legally you need to go to your local Citizens Advice Buro and make an appointment with a lawyer there. you are covered by the sale of goods act at what is considered 'reasonable' life and 'typical' use. I don't know your case so I dunno where you will stand, but they will. the contract is with the shop, or if you paid by credit card, with them (which can be really helpful in cases like this, I have had Visa hit Dixons before when I got a 'not our policy sir' response, Visa are the shops customer, you are theirs - it is whoever you pay. Visa are not a small customer) and how they deal with cannondale is irrelevant, it is their risk, not yours.
Good luck and make sure you tell everyone you know, the full facts, the only way to win really is to reduce their customer base until they go bust, meanwhile support your good LBS by paying that little bit more for bits from them to keep them going and tell everyone how good they are...... so on that note.....
big vote of THANKS to ADDIKTION CYCLES in St Albans for being good eggs, helpful, knowledgeable, friendly and patient with my random requests.....and THORNTONS CYCLES in Rugby for the the same reasons.