To send a message to our elected politicians. That's why I did in the European Elections.

No manifesto? So what, when our current crop of politicians don't implement their manifestos or even do the exact opposite.
No elected leader? You think May and Corbyn are a better alternative? May and Cable have both resigned anyway. And this isn't a General Election so there is no risk of instilling Farage in Number 10.
The one policy is to respect democracy. Implement what we voted for which hasn't been implemented yet.

Which elected leader with their manifesto they are faithfully following do you think people should be voting for instead?

The Tories and Labour have a chance to listen to the fact the public isn't happy with their current trajectory and change, or they deserve to die. Personally I hope the Tories listen carefully to the message being sent and adapt in their current leadership election and get us out of the morass that May dragged us into.