There should be some kind of receipt that was printed showing the transaction, even the first one done as return w/o receipt, because they have to account for records in the system at the store. Did they not give you one?... I don't have a store receipt on hand right now, but there is usually some kind of store number/info, and either cashier/transaction number info printed on it they ask for (when I had them do it by phone once). Did the same cashier do the return and correct purchase?
I'm kind of confused, lol, but if you did a return for store credit, you don't usually lose your points, but when you use the store credit-you don't gain any points, unless you end up going over the credit amount and pay out of pocket for some. At least that's how my points have always worked when I did return for store credit... because you already spent the money and got the points, you're basically just doing an "exchange" for other merchandise, not spending new money out of pocket again... does that make sense?
(let's see if I got the situation right? :-\)
So, if you were rang up for the wrong item, and they did a return for store credit.. Did they actually charge your card/pay cash first, then do a return for store credit? If that is the case, then you should get points for the purchase that was returned for store credit, but when you use the credit in store-that transaction wont receive points... But if your card wasn't scanned for that first wrong purchase transaction, those points wont show up on your account and you are owed them.
When you used the credit to get the correct item, you don't normally earn points on the credit part, and then got the difference back as cash.. and you scanned your card this transaction and got the point perk--which is the transaction the Sephora people are looking at...
Did I get that right? haha. You will have better luck by phone getting your points. I wouldn't trust in many service people by web to get this understood on Facebook. But by phone it should be pretty easy to understand and get your points.