RYR-738-JOCKEY, you mention that....
RVR is 350 and then the touchdown zone lights fails. The controller should both know that the required RVR is then 550, and more importantly advise every aircraft of this ("..below minimums..").
I would suggest that the reason the controller doesn't make a sweeping statement like that is because the minima can be different for different operators/types.
If the above case happened to me, all I need to do is adjust required RVR to 300m, not 550m. It would be a bit time consuming to for a controller to have to dig out details of each individual arrival's required minima, so they just leave it up to the pilots.
pbakes