I'd call them, its more direct and if they try fob you off, demand to speak to someone higher. They damaged your property, they must pay for it, simple as!!
Where did you go in York jsut outta interest as i live there.. North Eastern tyres on Clifton Moor were brilliant when i used them btw, for future reference
I went to a place called just tyres, up the road from the big halfords and kwik fit.
Last night i had to nip to city link which is right next to north eastern tires at clifton moor, so on way back i called in at them, they were just locking up and when they saw me approching opened back up again. They were very helpful and polite.
I am going into them tomorrow when i am through at York as they are going to check my Tracking for free, and if its out, can do it for about 25 pounds - which is a very reasonable price.