I completed a Offer Wall Task but did not receive any Gems.
Dragon City uses several third-party Ad providers.
So, if you haven't received your reward, you should always contact the offer provider directly, as they will be able to track your activity and check if you have completed the offer(met all the requirements) and not us.
IF, however, you have already contacted them and HAVE ASCREENSHOT that proves that you should have the items, please attach a screenshot of this confirmation and we will happily provide you with the resources you deserve.
Please find the company you require below and contact them by following the steps:
1. Click the "Support" button on the bottom left corner of the offer wall.
2. Choose the offer you have not received credit for and click the "Report" button.