UPDATE: We finally figured out what happened! My son's account had been hacked and someone stole the robux as soon as they hit the account. We didn't know it had been hacked because this was the first time he had anything to steal. If your robux don't show up in the account, be sure to check the "Transactions" section under "Trade" to see if someone stole them. I must say the Roblox people are VERY slow about responding to inquiries. They also have not restored our robux or refunded our $$, just reset my son's account. Amazon was helpful; Roblox was annoying.
Original review: I agree with the people who say this is a rip-off and I don't understand why it's still available on Amazon. I bought this for my son and gave him the code. He entered it into his roblox account on our iPad, it said it was redeemed, but no robux showed up in his account. I tried doing it, in case he typed the code wrong, but then it said the code had already been redeemed. After many phone calls with Amazon, I sent all the information about the problem to Roblox, but I never heard back from them. Complete waste of money.