At the bottom of this page, you should see a contact button.  You can use it to contact us regarding an ad you want to report.

While filling out the contact form please:
  • Specify the game correctly from the drop-down,
  • Select Ads as the issue type,
  • Make sure to include your country information in the message,
  • and, if possible, add a screenshot of the ad.
This will help the team identify the ad and quickly take action.