Beware of "VISA fraud department" scam!

I just got a call and it went something like this:
"Hello, may I speak to Mr Wick?"
I always get suspicious when people don't use my correct last name, but regardless, I answered:
"Speaking."
"This is from the VISA fraud department, your visa debit card was used in a suspicious transaction, a withdrawal of £300 from a cash machine, blah blah blah...."
"Excuse me, but can you tell me why the transaction was suspicious?"
"It was made at 3am."
Ok, at this stage I knew what I had on the line. I mean come on! How is a cash withdrawal at 3am suspicious? And would VISA *really* call me, using only half of my last name, because of a withdrawal at 3am? Especially considering that VISA has nothing to do with cash machines, nor withdrawals from a debit card? Do they really think I'm that thick?
"You know what?" I said, "you can take that VISA fraud department *scam* and ...."
I was interrupted...
"Fuck you!" *click*
How rude! I was just about to tell him where he should shove his scam, and he didn't even want to listen!

Anyway, the scam works like this:
They will recommend you to call your bank for one or another reason. It could be to report the fraud, to verify that "VISA fraud department" is in fact real or whatever. The details don't matter.
The reason they want you to call your bank is that when they hang up, they don't really hang up. Just stay on the line. Because they were the ones calling you, and not vice versa, the line is not immediately disconnected, so when you pick up the phone again to call your bank, they're still there. They fake a dialling tone and ask you the security questions, verify to you that they are real, and voilà, maybe make sure you know your credit card number and expiration date, etc. - *then* there will be fraudulent transactions all right!

Anyway, this only work on normal land lines. It doesn't work on VOIP phones, and I think not on mobiles either.