plastic door sills

Can anyone help. We have had new doors and sills fitted the sills fill with water which does not drain away. How can we unblock them? Grateful for any help.

Where is the water gathering? Your cills should be horizontal in one plane and angled away from the property in the other in order to shed rain. Where's the pool?

The sill has 2 channels in which the water is gathering. There are drainage holes but they might be blocked up. I have tried to unblock them with no success.

Hmm.. A photo would help. If (as I suspect) you're talking about the bottom rail of the door frame (as opposed to the cill it sits on) then it shouldn't fill up right to the brim. Then again it shouldn't get that much water in it consistently if the door seals are working OK. The drain holes at the bottom of the rail should be underneath at the front (not in line with the top ones). The normal place for them is in the little bit that overhangs a small step up in the cill. Try poking a bit of fine wire up this gap in case they're gunked up, though being new they shouldn't be.