Hi Stevie,
Thanks for your interest in this. We also received your email enquiring about this so I will respond to both here.
The Private Messaging app is still in development. It was scheduled for last year but some delays meant that the app has not been released yet. A few weeks ago we sent an email you our VIP members notifying them that a number of apps would be released in order to catch up on the delayed apps in the months of May and June.
So, to answer your question, no it is not available yet, but it will be soon!
Kind regards,
James