start/stop issue

Hi folks, looking for a bit of knowledge to help me understand a start/stop niggle with my 2026 model A3 S Line 35 petrol. The engine has suddenly taken to cutting out without warning. Doing so at 70 mph on the motorway was terrifying lucky I managed to dip the clutch before everything locked up. It has done this at various speeds since that first experience. I've been back to the main dealer who advised do NOT turn the stop/start system off and having done so touch wood no more cutting out incidents. I usually did turn the system off as I hate the start/stop operation but now it doesn't work at all. The main dealer can't look at my car for about three weeks and won't supply a courtesy vehicle while they hold onto mine. The car is six weeks old, brand new and has 548 miles on the clock. Any ideas or advice would be welcome.

Edited 1 hour ago1 hr by Paddington
misspelt word