Findo says
Unfortunately this does happen and the CAA know about it but are doing nothing to stop it.
MATS Part 1 SI 3/2001 says
On being informed that an aircraft is manoeuvring in accordance with a TCAS Resolution Advisory (RA), a controller must not issue control instructions to that aircraft which are contrary to the RA communicated by the flight crew.
At the end of the day, the only person who can stop avoiding action in the vertical plane being passed if it's not appropriate is the controller.
See, I do read some bits of the MATS!