I thought I was unlucky, and this only happened to me.

I had the same issue with my '96 A8 QS. In my case though, I went the brute force route the first time around, and bust the spark plug. Snapped clean in the hex part of the steel body, leaving the threaded section and the core in the cylinder head.

I ended up knocking the core into the cylinder, and driving in a special tool from Snap-On into the resultant hole in the threaded section. This tool looks like a spline key, but it's different - the teeth are square, sharp and slightly skewed, in the left-hand thread direction. Because it's hardened, the teeth don't wear, and it removed the plug core easily. It's a 1/2 square drive.

Once out, I used a vacuum tube to remove the porcelain particles. The central electrode came out with the upper part of the plug, when it snapped, so there were no steel fragments to worry about, but a magnet on a slim flexi probe would have sorted that out.

That's what I would do, took me 20 minutes, and the cylinder head didn't need to come off.

I wish I had the nerve!:o

Spoke to A4 Audi last night. Apparently, the plug isn't siezed at they can move it a little, but they said it's cross threaded and the swarf is preventing removal of the plug - it just sticks dead after turning a little.

I can't afford the 'head off and send to an engineering shop' costs, let alone the 2 weeks suggested to get this done but there must be a better way, surely?