OK so without boring you with the details, I needed to factory reset the controller and start again.

So controller reset, add hot water manually - Water sensor added fine, BDR91 for water fine, then it asks for heating controller which also bound successfully. (both BDR91's had bene fully reset prior). And lo, hot water working perfectly!

But when I come to add the first HR92 (single zone, nothing unusual) it asks to bind the sensor, which binds successfully, sync then happens and the zone name appears on the HR92 - BUT then it then asks for the ACTUATOR to be bound. Now its not clear but I guess it is asking for the BDR91 that is the heating controller. This BDR91 will got into binding mode (remember it has already been bound via the hot water) BUT it fails to bind a second time for the first HR92.

It does not seem right that the controller is asking for a BDR91 to be bound twice, so I am stuck? Any suggestions welcome please!

PS - HR92 was fully reset, menu plus battery change plus binding clear). BRD91 are away from each other and not near large metal objects.