Update:
I rang before I set off to ATS last Friday morning and as expected, they hadn't had the PS5s delivered. However, they did some digging and there was a pair in their Driffield depot. So the manager drove to Driffield (a 120 mile round trip) to pick them up on his day off on Saturday and they were duly fitted last Monday. Great service from the manager who could quite easily have just said they didn't have them.
Not tried them in anger yet so will see what they are like.