Yes, I, too, just show my Thai pink ID and off my post goes, letter or box. The only questions I get are "over night" or just registered.
EDIT: But that was not the issue. I should not have included that.
Bedbugy, As Jerno said, punctuation and separate sentences would help. On re-reading I think you were saying you wanted to close the PO Box you have had for 27 years and get your deposit back. The PO wanted identification. Over 27 years you would have had to renew your passport several times, just like the clerk said: 3 different passports on your record. So they want to see the current one to identify you are you before giving YOUR money to someone else. Right?