Leaky Boiler?

[sustech]

I Have a Glow Worm Flexicom 18sx, which I have to up the pressure on every couple of weeks or so.
I know there must be a leak. There was a wet patch under the boiler yesterday when I had to add water.
I rang for someone to come out and have a look and they said that it may not necessarily be the boiler as "water will leak out if the pressure reduces".
Is this the case? I don't want to pay for a call out if it is a problem with a different part of the system.

 

[crashndie]

there is prob a leak internal on the boiler place a dry bit of cardboard under the boiler and see where its dripping from