[pothole]

You are correct in part, Mike. What happened was I turned up with the cover off, we spent a couple of minutes together looking and listening and agreed to change the top pulley. They called back, said that this did not fix the problem but that they had noticed that the crank pulley was polished suggesting slipping, so we agreed to change that next. Time spent "diagnosing" in this case was minimal.

All I am asking for is a handle on the actual work done, I am capable of factoring in additional time for the things you mention. I am roughly aware of the time required to change the belt, which isn't much. But I am not sure how long it takes to put new pulleys on, I've never done that myself. Again, my feeling is that it's a very small job.

I am realistic about the fact that these people are in the business to make money. But I also want to be treated reasonably. When I ran BMWs, I had a specialist that was very reasonable and never fluffed up the hours to inflate the bill. Over time, they earned my confidence and in the end I gave them more work because I didn't feel the need to do much myself because they were both competent and only charged for the work they did. I am relatively new to this Porsche specialist and in that context I believe a healthy scepticism is required.

It's costing me approx £350 ($550), perhaps £150 in parts, to have the pulleys replaced along with a new drive belt. That's not outrageous, but my feeling is that it places them in the run-of-the-mill category. There's no way that my previous specialist would charge me £200 to take the belt on and off a couple of times and bolt a couple of pulleys on.