Just played a game, and my wife (Yes me and my wife play together) accidentally bought 2 sight stones 
and found out that they can not by "undone" (refunded) in the shop. She never left fountain, and tried to refund one right after accidentally buying the second. I figured its because it is a refillable item.
But I think even items like this should be refundable if you haven't used any of the active refills yet.
KaRniVooL131 votesjust went into custom game to test i bought 5 sightstones and undo all of them no issues. maybe she used a ward? maybe she thought she was in rage of fountain and just stepped out ?
Romans VI XXIII1 votesno she had "B"ed back and was standing in the middle of the fountain. idk it was just weird
Ethan Allen1 voteswhat champ was she playing. There is the chance that if she was playing something like zyra, teemo or nidalee that something of hers did damage after she bought them.
Romans VI XXIII1 votesshe was playing janna, so no.