Potterton Puma Combi 80, Pilot light continually keeps going out?

I have a Potterton Puma Combi 80, however, for the past 2 weeks the pilot light continually keeps going out - when the bolier is not being used either for hot water or central heating.
When the boiler is being used for either function, it works OK.
When the boiler is not being used for either function, the pilot light goes out. It then has to be re-lit for the boiler to function, this is occuring everyday. Many thanks for any advice provided.