Alan, I did the same with my previous bank (Co-op) with charging them for a letter I had to write to sort out their error... they paid it without question!
Now with Lloyds TSB, and whilst I've had a couple of problems, they've been very helpful and quick to resolve them so I'm happy to stay there.
As for estate agents...... well, this is a family site so I'll refrain from comment!
[Edited on 26-8-2005 by NBs996]