I think whoever you spoke to was uninformed. What I took a picture of IS what they look at and them punch in the 30% discount. If you are having an issue in the store you can always use it online.
Two people above you posted that they thought it was a very nice piece. As for being able to remove the pendant from the chain: I don't know for sure, but almost every necklace with a pendant I've ever bought could be.
I received my eCertificate today, The used the old bait and switch! States you must spend $99. NOT the $79. to use it. Oh, and it expires on the 13th!! What a joke.