Leaking box gutter in conservatory.

[Froggy95]

i have had water leaking from the corner of my conservatory, and about 1 metre along the box gutter inside. This doesn't happen when it's raining, seems to happen overnight only. Could this be overnight condensation, and how does it get into the box gutter, if rain doesn't.
I have had 2 builders looking at this, one put a grey paint all over inside the guttering outside, another filled any gaps he could see with a underwater sealant, yet there is still water coming in from the corner and a little way along the box gutter inside. You can probably tell I know nothing about these things, just what they have told me. It seems neither of them want to come back, as my calls are unanswered. I am disabled and can't get up a ladder to see if I can find anything obvious, does anyone on this forum have any idea why this is happening and what can be done. The conservatory is 9 years old, and I haven't had a problem with it before.
Heather, Reading.

 

[Bosswhite]

Sounds like it is Box Polycarbonite Sheeting, when its cut to fit,a closure seal is normally clipped over the edges top and bottom to stop condensation/insects/dust building up.
This may be faulty or a pinhole on the outside of the box channel

 

[foxhole]

Sound like condensation, the roof is not always in full contact with the top of the walls, mine had simple rubber flap to keep out wind but would not prevent condensation dripping out into gutter.

 

[Froggy95]

Thanks for your replies, I have had two conservatory fitters look at this, but still have the leak, am I asking the right people, or should I be asking a roofer, or upvc window fitter to look at it?
Heather.