Why, oh why has no-one offered the timeless resolution of 'turn it off and turn it on again'?
Fujitsu charge thousand of pounds a day for that advice. Me, I'll suggest it for nothing.
You always used to be able to tell a crap PC consultant because there answer to everything was to run check disk. (Those of us with any savy used to just run System Restore

).
However this was surpassed by a not so friendly CS person at Sky yesterday. My broadband went off the air at about 3:00pm and after 10 minutes I rang Sky. The solution - recycle the power on the modem and if that doesn't fix it, don't worry it will come back later.
In the meantime I was supposed to do what........
When it hadn't come back in the hour I decided to do my own diagnostics. Eventually, after checking all the cables I changed the Micro Filter it came back.
As I had only put a new filter on a couple of weeks ago, for a fault that wasn't a problem with the M/Filter I sort have thought it would be okay - however Sky did not know this.