I've just bought a new single din headunit for my fabia, and have the fascia (read: plastic strip) from skoda to go at the top. I've tried to fit it but there just doesn't seem to be enough room to fit another harness behind the bloody thing. It barely fits with the stock harness. Is there a knack to getting this all to fit behind? Cheers. 

You should be able to tuck the wiring below the radio (behind the little cubby hole). It is a bit tricky and does involve a bit of trial and error to get it to tuck behind there nicely but you'll get it in the end.

Yeah, with a lot of patience finally got the bugger in there!