If he still around ask him how many amps are in your cascade chain and whether he working down the chain from the o/e FN node on his own or with help?
The outages may well be the work he's already doing (or a colleague) upstream.
You appear to already have the new channel plan with 4 possible upstream 6.4MHz RF with 200khz guard bands (24.4, 31.0 , 36.6, 43.2) in space of 3 typical existing centre frequencies (27.4, 35.8, 45.8, ) previously.
Theoretically I think you could get 6 x 6.4MHz x QAM64 channels from 17.8MHz thru 59.8MHz based on those centre frequencies just before replacing legacy 5-55MHz DOCSIS Bidi amps to accommodate the (euro)DOCSIS3.0 (5-85MHz) upstream spec and expanding upstream capacity further.
However VM may be trying to defer replacement amps in order to accommodate wide bandwidth DOCSIS3.1 amps for OFDM with bottom,mid and top band splits. Replacing all UK (or large proportion of legacy Gerold) equipment is not something you leap into without significant planning and you certainly don't want to do it twice in as many years (usually only within 2 decades or more if you can stretch it)!
These things can therefore take significant time….(DOCSIS3.1) OFDM is still probably a a couple of years away yet from practical commercial quantities at least?
I also suspect VM will want to leapfrog from current 8x4 DOCSIS tuner to 24x8 channels and by-pass Puma6 and Broadcom equivalents before trialling a SuperHub 4 version. Interesting times…..