So I finally spoke to the dealer and he has kindly agreed to replace the gasket with the caveat that I also put down a contribution towards it as well (about a third of the cost)- the rationale being that I am getting a new one on a used car (go figure). I think that's the best I'm gonna get from him to be honest. Apparently it's about 600 quid for parts and labour! On the other items, I am trying to get them resolved at the same time while the car is in, and I feel it is going to be another uphill struggle, but this is a small win at least, and so far it has been fairly amicable. However I won't give up until everything I want fixed gets done...