Apple Users - All transactions completed on iPhone, iPad and iPod touch are handled directly by Apple. Please contact Apple Support via the following link if you wish to request a refund:

Android Users - If the purchase was made via Google Play, then we can indeed assist. (Please keep in mind that we will only refund a purchase within 7 days of the transaction. If this request is outside that 7 day period, then we cannot refund you in most cases.)
We'll need two things to do this. Firstly. please send us a message from inside the game so we can get your game ID. Then just forward through the Purchase Order Numbers or Gmail Address (the order number usually start with "GPA").

If neither of these options are available, like in the case of fraudulent card use, you best option is contact your bank and Google or Apple to get any extra transaction information.  In those cases, we have no way to access the transaction to refund it from our end.