You can contact us from inside the application. Simply open WhatsApp and select: Options > About > Contact Support. Please write a detailed description of your problem in the email. You will need an email account set up on your phone in order to contact us from the app.
Note: Starting on November 17, 2014, Microsoft changed the way email messages are delivered to Nokia devices, and as a result, you may be required to take actions to continue using email on your device.
WhatsApp Support Team