For the record: My dash vent flaps were fixed at the OPC. I don't want to jinx myself but it looks like the work was done well ... no rattles anywhere.

While the car was there, they also took care of three "workshop" items (no recall problems but little things they have found a better solution for meanwhile or they've seen break in the past).

WS46 - fit seal on left bulk head cover (over pollen filter)
WS47 - fit washers (?) bolting roof motors
WS56 - new bolts for front boot lock