[QUOTE
I've had a real positive windshear at 39000' over Paris - we went from a 40 kt tailwind to a 20 kt in a couple of seconds whilst flying at M0.78. The most effective, safest initial action is to pull speed and select it back (this changes the thrust mode and ATHR is far more responsive. Then we slowly used some speed brakes. We didn't overspeed! In FCTM take note it says if the trend arrow reaches or slightly exceeds Vmo/Mmo then go speedbrakes and THEN selected speed. It goes on to say if it significantly exceeds Vmo or Mmo i.e. it's happened - pull speed and select lower, consider AP disconnect and use speedbrakes with care considering the pitch up moment whilst close to the ceiling[/QUOTE]
Only flew the bus for two years and had one over speed in a similar situation to the above. Having flown Boeing's for quite a few years before the bus I treated the bus as if it was an aircraft that wasn't performing as programmed into the FMGC. I immediately disconnected the A/P, reduced the thrust manually, and gently pulled the nose up - and 'hey ho' we were out of the over speed condition almost immediately. In a serious over speed I would use the speed brakes.
Why you would continue to use use the automatics in a degraded mode such as 'selected speed' is quite beyond me. Airbus kindly provided you with a side stick so use it.