Sorry to be a pain in the backside, but
When your car goes into the garage to be serviced, or upgraded/improved, are you not without it for that process???
If your computer is taken into a shop to be upgraded, are you not without it for that period?
Alot of upgrades require you to be without something for a short period, but you dont mention these?????
I agree..... they could at least do the upgrade overnight, or in stages to cause less disruption to the already poor service, but..........................