If this has happened to you this is direct from the EA FAQ (https://help.ea.com/article/the-simpsons-tapped-out-faq)
1. How am I charged for donuts?
You are billed/charged the same way for any other purchase on your iPhone/iPod (or Android Device); through your iTunes(/Play Store) account. If you have any billing disputes or questions, please contact Apple (or Google).
2. I purchased something in-game, but I cannot see it. What happened?
In some you may need to exit the game and restart it to access your new content. If that doesn’t work, try turning off your device and restarting it.
3. I still can’t see my donuts. What next?
You can visit the FAQ sections at http://www.apple.com/support/itunes/store/games/ and contact Apple for any billing issues. (Google https://support.google.com/googleplay/answer/1267137?hl=en)