well garage has replaced the thermostat and checked water pump, cleaned the radiator and bled the system and....
well its slightly improved - starts warming up quickly but unless under load it stuggles to get up to normal running temp. however once normal temp reached, traffic or hills, it then seems to hold rock solid. obviously its now a lot warmer than a few weeks ago so dont know if weather or thermostat have caused changes. did notice when i removed the cap on the expansion tank when cold that level rose by about 1cm - does this suggest air still in the system.
my garage is baffled and is now trying to say all is ok but i dont think so. any views appreciated plus can someone tell me where all the points are to bleed the system as i still suspect air in the system. cheers.