Here's one that'll make you smile. I can't be to specific because of commercial confidentially issues.
We recieved a number of support calls yesterday from private users. They had been complaining to BT about charges incurred when their computers repeatedly dialed the access number of an ISP that they didn't use (in fact most of them didn't know it was an ISP number). BT in their usual cock-eyed way had spotted that we are a customer of this ISP and told the users that it was a number assigned to our business. It wasn't, in fact it was nothing to do with us. We told the users to check for viruses.
However the circumstances made us suspicious that some script kiddy somewhere was trying a sort of telephonic DDOS against the ISP.
The killer is that the number used was an 0845 number.
:o)
Keith