Whatsapp bans users for using third part app for whatsapp named whatsapp plus and its been stated in their FAQ section

WhatsApp Plus is an application that was not developed by WhatsApp, nor is it authorized by WhatsApp. The developers of WhatsApp Plus have no relationship to WhatsApp, and we do not support WhatsApp Plus. Please be aware that WhatsApp Plus contains source code which WhatsApp cannot guarantee as safe and that your private information is potentially being passed to 3rd parties without your knowledge or authorization.

Please uninstall your application and install an authorized version of WhatsApp from ourwebsite or Google Play. Then, you will be able to use WhatsApp.

In reply WhatsApp Plus says

All the whatsapp plus users do give a negative ratings and review on the original version on playstore or appstore…

The company is now asking users to uninstall WhatsApp+ and install an authorised version of WhatsApp from official website or Google Play to reuse the service, although the 24-hour ban period will reportedly remain in effect for the full duration despite replacing or uninstalling the app.