Finally got my car back. That's 1 good thing. And I know I'll never go back to that mechanic again and that's another good thing.
Outcome was failed oil seals on the cam pulleys, which were replaced, in addition to the cam chain which was replaced. Likely factor was overheated engine, which has occured in the past due to failed low-speed fans.
He also mentioned , as a side, that they suspected some problem with the cats due to ?blockage. They opened them up, removed the catalyst honeycomb, and welded it back up!
The car certainly drives as it should again, but with obvious new exhaust tones, as can be imagined. Luckily I have a new set I've been waiting to put on.
Thanks again for your advice, I managed to sound like I knew what I was talking about when discussing with the mechanic.