Battle.net Balance cards just bought code not working

I bought some Bnet cards from my local grocery store, been about an hour since, and two of them are not working at all. have the activation receipt, but since they’re gift cards YOU CAN’T RETURN THEM. I put in a ticket, but am coming here to ask if there is an activation time? Is there a certain pattern I have to put the code in? It’s a 21 digit code. Bought from legit store in my state on the list of retailers.

Community members can’t assist you with a purchase issue. Open a ticket with the staff.