Hi Nigel,
Thanks very much for your response and your feedback.
The IHG.com and Crowneplaza.com site we have no control over - so we cannot add rel=canonical tags to them.
We will start 301 redirecting all the http URLs to https. In regard to the robots.txt, our developers have disallowed wp-admin pages, is this different to no indexing? - https://christchurch.crowneplaza.com/robots.txt - and should we also no index /wp-admin/admin-ajax.php ?
We have built a sub domain before for auckland.crowneplaza.com and it is ranking first in Google for its brand name 'crowne plaza auckland.' We didn't have these ranking issues with that sub domain like we are having currently.
Thanks again,
Tim