I don't know about JAA rules, but what you have described already matches CAA guidelines - there was a SI issued about this not so long ago. As your profile says you're an ATPL holder, I'm surprised you haven't seen it.
As controllers, if we see a loss of seperation developing, we will continue to give avoiding action as we have always done, however once we are informed that a TCAS RA has been triggered, we will give no further instructions, only traffic information, until the situation has been resolved and the aircraft are back under our control.
Remember that the picture we see is up to ten seconds out of date, because of scan rates, transmission and processing delays. As far as TCAS being "wrong", its probably theoretically possible but we work on the principle that it's infallible if followed.
Hope that helps
cdb
Edit. Cobbler New guidelines are not to give ANY avoiding action, vertical or horizontal, once informed of the RA. I believe this is because of concern that the angle of bank used for an avoiding action turn could decrease the climb rate below what is required to satisfy the RA.