Yup, well GN have just lost my (admittedly small amount of) business permanently over this.
I have to journey into King's Cross from Potters Bar and back a couple of times a month, often with a disabled friend. Usually this is on a weekday, but recently we needed to do it on Saturday 9th July. Imagine my reaction when I looked at the NR site just before I had to set off, and then what I found when I looked on this forum to see why that might be.
So what did we do?
We caught the 298 bus... not to Potters Bar Station as usual, but in the other direction to Cockfosters, just ten minutes down the road, and got the tube from there. On the way back we made the change at Southgate instead of Cockfosters, which saved us 60p and a set of steps (handy for my friend who has limited mobility).
We've now decided that that will be our permanent route into London, for various reasons:
1. We're guaranteed a seat on the tube (especially if we start at Cockfosters rather than Southgate); contrast that with trying to squeeze on at PBR when you're the last stop before Finsbury Park. Also, the Piccadilly trains have more luggage space available.
2. The numerous ECML tunnel entrances play havoc with our ears (I don't know how the regular commuters stand it) in a way that the fewer Piccadilly ones don't.
3. My friend doesn't have to traverse the entire length of King's Cross station from and to her train.
4. You don't have that delightful situation where you emerge from Potters Bar station after about 9pm (the exact time isn't made clear anywhere) to find that they've closed the normal station entrance, so you have to hoik all the way up round the back of the station, then down and up under the railway bridge, just in time to see your bus pull away from the front of the station. (Sometimes that happens even when you come out the front entrance, as the bus drivers seem to like to leave earlier than the indicated time.)
5. It costs less - even with my friend's Disabled Rail Card for National Rail and the fact she has no Freedom Pass for the tube (only for buses), it's still between 40p and £1 cheaper for us to do the tube route, depending on whether we start at Cockfosters or Southgate.
6. BUT MOSTLY - it seems that there's a far better chance that the bloody train will actually be running!
Thing is, were it not for GTR's cackhanded handling of this shift business causing such problems on that Saturday, I never would have bothered to find out that alternate route.
(Full disclosure: actually, I had researched & considered it previously, but my friend wouldn't countenance it as she's not generally keen on the tube... but having been forced to try it due to the GN cancellations, she now much prefers it and it will be our future travel method.)
Obviously not everyone is lucky enough to have such alternatives, but some other people must have, and all this hassle will only serve to decrease their revenues...