Items bought through our games (In-app purchase) are generally non-refundable. In some special occasions there can be exceptions. The transaction process is controlled by Apple and Google.
Please contact Apple or Google support teams for refund issues.
Visit Apple support and select the "contact iTunes store support", then "Purchases, billing and redemption" and select the option that fits you.
Visit Google support and perform a serach, or "Contact us" button on the page to reach a Google customer support represetative.