Andy, I had the misfortune of having to visit a kwik-fit branch today needing tyres for my van and managed to upset the staff before i left...
Whilst waiting for them to pry the cash out of the lease company for my tyres a bloke came in for some winter tyres for an Audi A4 as he was heading to Germany for a few weeks, Kwik fit monkey fed him a line about his warranty and insurance being invalid unless he fitted the same brand winter tyres as his OE fitment summer ones!
Suprise suprise they were Continentals which he just happened to have in stock and for the bargain price of £1400 for a set of 4 18" tyres....
Bloke looked shocked but was actually about to buy them until i cut across and told him to try mytyres/black circles etc and also to try and get some 16" wheels and therefore cheaper tyres, Kwik-fit monkey then nearly burst and needless to say i didnt get my tyres fitted haha!