Right, I've just bought a galaxy mk1 diesel, W reg. I was having same issues, lack of air flow, steam etc. Got new combination filter off eBay and followed Seatkids instructions. However when I got to reassembly it was impossible! Far too big, wiper bolts solid etc. I had to come at it from a different angle. I got the cordless grinder on the filter holder and cut the raised cover off. I then ran the grinder round the entire front edge of the filter holder and the centre bar with a flap disc in and removed 2mm approx of plastic. This was prefect, it let the holder and filter in and where it needed a wiggle it was now far more flexible! Very easy fix, if you're handy with a grinder. Hope this helps someone, I know 14year old car, probably not many bothered now!
P. S. Date stamp on original filter of 2001!