Having been the victim of identity theft on my AmEx Platinum card some years back, I am very sympathetic to fraud prevention efforts and certainly don't mind confirming a large or unusual charge.

However, the fraud prevention software now being used by BMO appears to be hypersensitive and badly programmed. Most recent example: a car rental preauthorization of $301 from Hertz resulted in a block on my account because it came from Oklahoma City when I was making charges elsewhere the same same day. OKC is Hertz corporate headquarters -- lots of charges are posted there for car rentals both inside and outside the US. And this is not the first time this has happened with BMO DC -- it also occurred with an Internet purchase from Macys that was billed from a central office outside my home state.

My account is otherwise in perfectly good standing -- well under my monthly spend limits, no current or recent past due balances, etc., etc. When I ask the CSRs about this practice I get the usual customer service doublespeak.

Has anyone else had this experience?

This may be the last straw for me with Diners. I stuck with BMO because I like having a card with a chip and PIN for travel outside the US, but if they are unable to authorize routine travel transactions like car rentals without blocking my account and contacting me first, the card becomes too unreliable for travel use.