If you want a refund, please log in to your Apple-ID and report a problem with the purchase here so Apple can refund it to you. Only they can help you with refunds with iTunes/ App Store purchases.
If they won't help you out or you prefer to get the Gold Bars credited, then send an email to our Player Support. Open the game and on the Start menu tap the Settings > Cogwheel > Help > Purchases & Gold Bars > Contact us. Our player support will probably ask for a screen shot of the purchase, so meanwhile, please log into your Apple-ID and and tack e screen shot of the purchase and receipt so they know which purchase it is regarding.