Hi Gwarpt1,
I only read down the first few replies, so someone might have already told you this.
I have been charged a few times when I've had no money in my account on direct debt day, I bank with the Natwest and everytime it has happened, (normally over a weekend), ive popped into the bank and they have given me a refund there and then (I get income support and DLA), they have always been really good about things, but of course they give me a telling off.
not sure how this helps, unless you wanna change banks...lol