My boiler won't stay lit. Pilot lights ok but when I release the button it goes out, any ideas anyone, I'm desperate for a shower in hot water!!

Sounds like the thermocouple has stopped working. It's the bit that sticks up in the flame - has a solid metal 'lead' from it to the gas valve.

What's the solution to this?

Nigel's the techno guru on these things (and most others).  If it is the thermocouple (easy to identify from Nigel's description) it either needs cleaning (turn everything off and scrape off any gunge) or replacing.  If it's a locally purchased boiler you should be able to get spares at Clibergas (need directions ?).
If you mean that the pilot stays lit but the burners go out, it could be the CO2 sensor.  If so, come back and we can chat about that.

It's possible but unlikely the thermocouple is just dirty  - they have a habit of splitting open after a few years - this is more likely.

The solution is to change it (I'm assuming you are competant at such things :-)). Clibegas don't carry spares but you will probably be able to get one at Blascos (near the police station in Tortosa). There are various sizes and shapes so take the old one with you. They can test it (or you can yourself if you know what you are doing). If it isn't this then it is most likely the gas valve.

You didn't say what make the boiler is - I'm assuming it's a wall hung gas water heater.

Nigel

Thanks for the advice, I have removed it and will take it to Blasco's on Monday .Hopefully this is the solution.