How many plumbers does it take to fix a Puma 80 boiler?

For the last week and a half of sub-zero tempeatures my wife and I have had no central heating. The agent that manages our flat has sent a plumber round to have a look at our Puma 80 boiler. He's now on his third visit and eleventh hour of trying to diagnose the cause of the problem. His efforts so far involve dismantling the boiler replacing a part reading the instructions on the back of the boiler cover over and over again and finally moving from one component after another blowing on them. If you're a plumber would it take you eleven hours to diagnose a fault with the central heating?

Alex Bray
December 2007