hi i've been working at home depot Canada for about 2 years now in the paint department..and unfortunitally this does happen sometimes... the best thing to do is keep a copy of your rebate and receipts..on the back there is a 1-800 number you can call and track your rebate or go online (i beleive the web site is behrrebate.com...dont quote me on it ) and type in your postal/zip code and track it that way also...
if there is any misunderstanding with the receipt they will simply toss it aside and move to the next..its unfortunate but they are people and they do make mistakes so protect your purchase, keep copies and look into it.
i had actually called for a customer once and the reason he didn't get the rebate was becasue they couldnt make out the street name..as simple as that.
Good luck!