The central locking switch at upper part of driver's door has broken internally, coinciding with an unlock problem with the keylock device. Only the driver's door does NOT unlock - but about 2% of the time it does.
My Audi is an A4 Avant, 2009.

I'm not convinced that it is only the mechanical breakage of a plastic loop inside the switch. Maybe it is a diode?

Any ideas about this from other owners?

I'm prepared to put up with the inconvenience against a possible high $$ repair cost from the usual Audi agencies.

Pages 34 to 37 in my owners manual describe and picture the small lock/unlock switch.