Economist Wall Mounted gas Boiler?

Happy New Year........the pilot light went out on New Years day and after 6 days of waiting for an engineer to call decided to tackle this myself, first problem was a broken wire to the ignition unit, now successfully repaired but now, even though the pilot light will light initially, it goes out again as soon as the gas control button is released (instructions state that this must remain depressed for at least 20 seconds), I have kept the control button depressed for several minutes but the result is the same, the pilot light just WON'T remain lit!
ANY suggestions would be most welcome as it is currently -6 degrees here, set to go as low as -20 by the end of this week.
Many Thanks