Behodar:

 

The Pizza Hut website, I think it was, used to have an example phone number "021 123 4567" next to the field. If you enter it in that format then it complained that it wasn't a valid number (until you removed the spaces). They did eventually fix it, but it took a while!

 

This was the same site that used to have an icon of a £1 coin next to the "pay in store" option (it was eventually changed to $1).

 

What annoys me even more, is when you enter a phone number, birth date, etc - and the site says "not correct format" but doesn't give any indication what the correct format is. I have seen this a few times but can't remember on what sites.