Glow worm compact electronic, sometimes ignites, other times locks out?!?

Hi,

I have a glow worm compact electronic gas boiler which is giving me some trouble.

When running hot water or the heating the boiler turns on but the pilot light does not always ignite. It more often than not flickers and then lock's out. Other times it kicks up no problem.

?????

Any help would be greatly appreciated.

David