How to ask for reimbursement for the app purchased from iTunes store
How to get a refund using iTunes

Launch iTunes on either your Mac or Windows PC.
Click on your name at the top and in the drop down select Account Info.
Type in your password when prompted in order to proceed.
Click on See All under your Purchase History.
Click on the arrow next to the purchase batch that contains the purchase you'd like a refund for.
Click on Report a Problem next to the single purchase you'd like a refund for, unless there is only one, then you may use the large Report a Problem button.
You will be routed to Apple's website. Just follow the steps after signing in and request the Refund option and explain why.

How to get a refund using the web
If you're not at your computer, or simply prefer to sidestep iTunes, you can still request a refund using any web browser.

Go to Apple's problem reports page: http://reportaproblem.apple.com/
Login with your Apple ID user name (typically your email address) and password.
Select the appropriate tab—all, music, movies, TV shows, apps, or books.
Find the purchase you want refunded.
Select Report a Problem to the right of the purchase.
Select the reason you want the refund.
Fill in the description, as appropriate.
Select Submit.

How to get a refund using your iPhone or iPad
Apple hasn't built any links to problem reporting into the iTunes Store or App Store apps, so if you're stuck using the web on your iPhone, iPod touch, or iPad as well. If it's more convenient, you can go directly to problem reporting via your email receipt.

Launch Mail from your Home screen.
Search for &quot;Your receipt from Apple&quot; if it's not immediately visible.
Tap on the receipt for the purchase your want refunded. (Unless you remember the date, there's no way to tell which receipt is which unless you tap it to open it, so you might end up tapping a lot...)
Tap the purchase you want to report.

Source.