We definitely want to make sure you receive HEARTS you've paid for. While in-app purchases usually deliver instantly, they may take longer on some occasions. When such delays occur, it means the purchase is still being processed. There is no need to try purchasing the same item again as it should arrive soon.
If you still haven't received a purchase made more than 24 hours ago, please contact iTunes support since all payments made toward the game are processed by Apple. You can reach them here: https://support.apple.com/
If these steps aren't helpful, please contact us with a screenshot of the receipt.
Apologies in advance for the inconvenience as we know you want to get back to your game!