Don't really see the problem
No one is forcing you to live in the sticks.
You don't move to a village in the middle of nowhere and then complain that there is no multiplex cinema nearby.
I f I decide to build a house in the middle of nowhere all the utility companies will charge me thousands to connect it up, which is why many opt for oil tanks, personal generators and digging their own wells.
As others have mentioned, there are alternatives for broadband. They might not be as good but that's what you get if you choose to live in the sticks.
Wherever you live you have to make compromises to an extent. I get good broadband, plenty of pubs and two local cinemas, but can't afford somewhere with a garden, get to have my lungs destroyed by pollution, and there is not much in the way of peace and quite.
I am curious as to exactly what they would have to upgrade given she is only three miles away, but £130k isn't that much given the cost of carrier grade gear, and the probability that it would involve digging up a road or two.
This is what happens in the open market, some customers are just not worth selling to. I'm sure BT would be happy to let her go to a satellite or wireless carrier rather than lose £130k on her.
If you want universal coverage then you have to nationalise BT Openreach (which I'm actually in favour of).