I've did the same, but this was their reply:

Hi,

Thanks for your message. Your WhatsApp account has been banned because your activity on WhatsApp is in violation of our Terms of Service.

We cannot comment on the individual reasons that have led to your account ban. However, the following actions provide examples of activity that will result in an account becoming banned:
Sending ads or any other form of commercial solicitation.
Sending spam or unsolicited messages.
Submitting content (in status, profile pictures or messages) that is in violation of our terms of service such as unlawful, obscene, threatening, harassing, hateful, racially or ethnically offensive or any other inappropriate material.
Being annoying to other users.
Being a repeat infringer.
Using an automated system or an unauthorized / unofficial application to send messages through WhatsApp.

Please review our Terms of Service to learn more about the appropriate uses of WhatsApp.

We currently do not have a repeal process in place for unbanning your account.

You can also read this FAQ article for more information on banned accounts: http://www.whatsapp.com/faq/en/general/23154266

Georgia

WhatsApp Support Team