I had a problem firstly when putting key in ignition and not sending a signal through to the stereo.
Then yesterday, my car wouldn't start, which again, I pinpointed to the ignition switch (behind the iginition barrel) failing to work properly. Just to let you know I personally found this a pain in the arse to fix on a mk3 Golf and would recommend getting a quote from VW people if cheap enough. I'm writing this because I couldn't find anything on the web for a mk3 golf to help me.
...however, It took me just over an 1 hour 15mins to fix (including head scratching time!). The switch itself is VW only and costs just over £20.
I removed all the plastic cowling from around the steering column, disconnect battery, unplug airbag lead to back of wheel, unscrew hex bolts from behind steering wheel, remove airbag/centrel, and remove 23 mm nut in middle of steering wheel. Then three screws hold both instrument stalks on and unplug all leads (remembering where they go, but don't worry they can't go back where they're not supposed to) Unscrew shear-off bolt clamping collar of the barrel holder around steering column casing (mine was just finger tight) Easy so far!
Now you will need a
Small fingered puller to remove the flanged collar in front of the small chunky spring. ...I didn't have this! so in the end I decided it was easier just to remove the steering column, which took me about 10 - 15 minutes longer, but involves breaking yer back trying to reach under the dash! There are two shear-off bolts which I had to drill/chisel to unscrew and further down some more bolts. (Remember to take the steering lock off with the key) This let me remove the whole column and I could then hold the flanged collar, while hitting the top of the thread on the colum with a hammer. Thus finally removing the collarÂÂÂ

Basically I found it a pain in the arse for what I thought was going to be a simple fix. Apparently its a common failure on mk3's and more tricky to remove than on mk1's and mk2's. Hope it helps. I'm sure someone will tell me I've gone about it the wrong way!ÂÂÂ

Thanks to those people!