Legally, I would be very surprised if your friend has a leg to stand on. It sounds exactly like a warranty issue. IANAL however.

It's also hard to argue anything other than inconvenience, it's not like the factory fault means the car is unsafe.

TBH if she really wants to try to get some compensation, probably her best bet would be to bring it up on Twitter/Facebook and try to get some publicity. You may be able to embarrass Vauxhall into responding that way, especially if you highlight the community nurse bit. I'd be a little surprised if it worked but you never know.