Problems with two-step verification on a new SIM I recently purchased a new SIM. When I try to install WhatsApp, it asks for a PIN that was apparently created by the previous owner for two-step verification. What should I do?
I just experienced the same problem and according to WhatsApp support there is no real solution for it.

I also got a new SIM with a phone number that was used by someone else before. This previous users WhatsApp account had two-step verification activated which means I couldn't activate WhatsApp since it was asking for the pin that I don't have and that can only be reset with an e-mail adress that is not mine.

The answer from WhatsApp support is to wait 7 days and then I will be able to reset the account without the pin. They said there is no alternative or other way to speed up the process.

Update 
The account reset worked as expected after 7 days.
Any messages that I might have received in the meantime were not delivered and deleted.

This whole process doesn't seem very optimal to me.