Paid but didnt recieve product.

Hello, I'm a big fan of the Minecraft Pocket Edition. I had previously purchased the "School of Magic" world pack by Cyclone Designs. It was great from the start, a smooth download, hardly any glitches, and amazing adventures. It made me look for another pack to add to my inventory. I found the "Advanced Dragons" by Pixelbiester for $10.99/1340 coins, so I purchased it. However the pack wouldn't download and it didn't add to my inventory at all. I went and checked the transactions on my Visa Debit through my app, and there had been a withdrawl for $12.31 from apple for the product (that I didn't receive). When I went to go look back at the Advanced Dragons pack in the marketplace, it only gives the option to purchase all over again. I would like to find a way to add the pack into my inventory on my iOS device, but if this cannot be achieved I would like a refund. Thank you for all of your help.