US Post Office Annex

I put in a request for a mailbox on December 31, among with paying the required fee. The next day was a holiday, so I assumed the box would be unlocked Jan 2nd. It was not. In desperate need of a check mailed to my address, I stopped by the annex to see if I could get my mail, as well as find out if there was a problem unlocking my box. No, I couldn't have my check, and no, no problem unlocking my box. Just didn't do it. "Maybe Friday or Saturday"! How can you deny someone their mail? Your carrier is on my street - why doesn't he unlock my mailbox??? This is not right.