My 04 A4 1.9 tdi has been struggling to start below zero degrees c recently, needing quite a few turns of the starter and then starting roughly.
I ordered a new set of Bosch glow plugs on Ebay from a German seller. I used the "best offer" feature and got them for £22 which I think is a bargain.
Set of 4 BOSCH glow plugs AUDI A6 1.9TDI 110BHP 130BHP GENUINE 0250202023 -NEW- | eBay
I also ordered a 1/4" drive 10mm deep socket to do the job.
Draper 12672 Expert 10mm 1/4" 6 Point Deep Socket | eBay
I fitted these today in the cold but I did run the engine for a few minutes first to warm things up and make old plug removal slightly less risky.
I very carefuly used a pair of long nose pliers to pull off the electrical plugs. my ones are electrical ones which did no damage to the plugs, maybe use a rag in the jaws of regular long nose pliers.
I found the 1/4" drive socket with a long and short extension to be just the trick for getting in behind the rigid steel and rubber coolant hoses and also down behind the fuel filter, so I didn't need to move anything out of the way.
The new plugs even came with pre greased threads !
Once all torqued up and electrical connectors clicked back on, engine cover etc, the car now starts first turn with no hesitation or smoke in the cold. Another satisfying DIY at little cost more quattro fun in the snow now