I have one of the priority care packages on my Infinity service - cannot remember exactly which. Service is delivered across my residential phone line. The advantage is that if my phone line fails, it is likely to affect Infinity so I get "free" coverage of that too.
I don't think we are singing from the same hymn sheet here. Have a look at
where we can see that it relates to voice services only. True if voice services are lost then it might impact on the broadband service but it has been reported many times on TBB that the broadband service has continued even though no voice service was available.
So turning this on its head, let us assume the broadband service has gone down but voice is still available. You may well have Total or Critical Care but as far as I can see this does not give you any kind of priority attention to restore your broadband service; even more so if your voice and broadband service is delivered by two different suppliers.
But sticking with the same supplier with a single line for both voice and broadband, I don't know of any ISP who will give a priority fix service, for an additional fee, if just your broadband service goes down when you still have a voice service. I stand corrected on that though.
So you fall back on your business interruption plan which may mean going to a different geographical location or invoking your business interruption insurance. If you are in the minority that has a duplicate broadband service, with physical different paths back to the exchange, then I suppose you are covered for some eventualities like fire, flood or worse like the area being sealed off due to a suspect package.
You make a risk assessment and have a plan according to your budget.