The oil I had on order for my gearbox has arrived today so I thought I would change it since it's a nice day. Slight problem.... I can't find the filler hole? I've searched the site without much success and my Haynes is not much better. Any ideas? Thanks!

filler hole on the side on the TDI.

You fill it until the oil comes out of the filler hole when the car is on level ground.

IIRC you can get quite a build up of sludge in the gear box so i got a garage to do it including a flush through with warm oil.

Its on the front of the box when you look at it from the front of the car about 150mm up, It takes a 17mm allen key (or and M10 bolt with a bar welded to it). Its quite difficult to fill the box though, I attach a pipe to the bottle and stab a hole through the bottom that you cover with your thumb when squeezing the oil out, then remove when you are sucking air back in. Makes it a bit easier.

HTH