Wouldn't make sense if they don't let you do that as you can just return and buy again?
I actually called yesterday to try to work this out, because I bought an engraved iPad last week (arrived yesterday) -- I didn't use the edu store when I ordered though, even though I'm eligible, because there's no discount, so that apparently that made things harder for this...? He actually suggested I go to a store and return it
Anyways, he acted like he was doing me a huge favor by escalating it and seemed think it will go through in the end, but I'm surprised they don't have a more regular policy for this. I'm sure others experiences might be easier, but I guess you might have to do some convincing...