Thanks everyone for your words of encouragement. I feel much better now.
I too only do very short runs, probably why I only get about 15mpg. I never have problems with the screen clearing infact its the best car I have had for that. I have never got more than 20MPG even on a couple of 80 -85 mph dual carriageway trips to Alnwick. 29 mpg is fantastic are you sure someone isn't filling it up for you when parked? I have considered the second car option as well but I think taxing and insuring two cars and then being faced with the choice of which one to use would be another dilemma.
I had my rear wheel alignment checked and adjusted at 5000 miles when the first set wore out and it made no difference. They wear quite evenly although the inside is very slightly worse. Have tried several different makes of tyres too. Still get 5000 out of cheapo Federals so I use them now at £70 rather than Contis at £130+.
I take the point about being unlucky but it's the parts situation that bothers me. Although several people have said that the parts are available they are not "off the shelf" like a more mainstream car's would be.
I test drove a Focus ST today, nearly as nice to drive, exhaust note under power sounds great, acceleration etc and with the parts and service backup. Still haven't made my mind up though.