I've used National once, to get from my parents home back to Sheffield. They where exceptionally helpful, and provided me with a Black Golf GTi for a fair price at such short notice. The car was in great nick, and really well spec'd. The price was fair, considering it was one way and I was then under 25.

I've never gone back to National, mainly becuase there's normally a better price, but in an emergency I suspect they'd be good to cover me again. They even understand the problems of smaller cars for tall people, and try to ensure that they don't give Corsa's to people like me.