Anyone using 'Nest', 'Hive' or 'Tado' smart heating thermostats?

[Kingy]

Its hammertime.

Tbh, followed the instructions diligently. Wiring was simple and straightforward. Everything correct (double checked). Switched on - all good. Then went to sync everything. Two boxes - the smart thermostat and the extension box linked to the boiler need to sync via wifi to 'the gateway' which is connected to the router.

So, Gateway connects properly. All three lights on, with one flashing waiting for the smart thermostat to link.
Activated that - No problem. All lights on.
Activated the extension box. (Which connects to and controls the boiler)
...Problem.
It won't sync. (So can't communicate with Tado server).
Checked instructions again.
Went back over everything, double checking and there is nothing wrong. (Wiring wise there is sod all to check as its only 3 connections in the boiler and then three in the tado extension box and all are colour and number coded).

Switched my BT router and 'Tado bridge' power on/off and and tried syncing again.
Same result.

FAQ suggested a factory (software) reset to check software (syncing) was set up 100% correct.
Did this, but as the three units have been registered once, I now get held at this point (screen) of 'installation' and cannot get any further. Aaaagh!

Have emailed tech support and told them whilst everything works as it should do independently, until it will all sync together it won't work. I'm assuming they need to sort it their (server) side.

Bit pissed off to be honest as a software issue is the last thing I thought would happen. Lets see what they say. Hopefully if they give their server a quick slap we will be sorted.