Amazon's policy is that refunds are not available for digital goods. If a user has a valid reason for a refund (e.g. the app is not compatible with their device) they should contact Amazon customer service by following the steps provided below.
1. Click this link: https://www.amazon.com/gp/help/contact-us/general-questions.html
2. Sign in with the Amazon account associated with the purchases in question.
3. Under section 1, "What can we help you with", select Kindle.
4. Under section 2, first select "Kindle Fire Apps" from the first drop down, select "Amazon App Store" from the second and "Unintentional purchase" from the third drop down.
5. Under section 3, select which contact method you prefer for an Amazon Customer Support Representative to get back to you.
PLEASE NOTE: We have absolutely no record of billing or account information and you MUST get in touch with Amazon using the outlined process above in order to be considered for a refund. Please enable a PIN on your device to avoid unintended purchases in the future. You can find information on how to do so here.