Is there a way to make Siri listen properly?

When writing a message using Siri, the software will stop listening for the message at the slightest pause.

For example:

Me: Send a message to John

Siri: Okay, what would you like it to say?

Me: Hi John...

Siri: Okay, your message to John is "Hi John", would you like me to send it?

And this continued every time I left a pause to think what I wanted to say next.

Really annoying.

Is there a way to make Siri wait and listen properly?