This article is from the Credit cards and Consumer Credit FAQ, by email@example.com (Steve Adams) with numerous contributions by others.
Yes, the Bankcard Holders of America includes a wallet-sized
Consumer Action Card with its pamphlet #14, "Consumer Rights at the
Cash Register." For a copy, send $3 to BHA, 560 Herndon Parkway
suite 120, Herndon VA 22070, or call (703) 481-1110 (their 800 number
is no longer in service) and ask for a catalog. The card gives you
something to show the merchant who won't believe your unsupported word.
The card has no legal force, but at least you don't look like you're
making things up. The pamphlet does the same thing, but an 11"x17"
piece of paper gets kind of bulky folded in your wallet!
Also see the pamphlets mentioned at the beginning of this file,
which are issued by the Federal Reserve. That should be official
enough for any merchant.