Make a note of every phone call and conversion, what was said and when. Their warranty is completely irrelevant, you're not claiming off their warranty, but are using your rights that EVERYONE who buys a car from a dealer has.

It's failed so soon after buying it that you are covered by the Sale Of Goods Act. You have to give them the option to fix it first, if they don't you can get it fixed elsewhere and bill them, but I suspect that would be very difficult!

You need to read up on the Sale of Goods Act, and if necessary get legal representation - Whatever you do DON'T just rely on what you're told on here. As far as I'm aware no one here has any legal training.

As for the comments about "what do you expect buying a car of that age" - Well, if you buy from a dealer one of the reasons you pay a premium is that you're covered if the car fucks up! The question should be "what dealer in their right mind sells a 100K Mondeo TDCi" !!