Ok, so we sorted the dreadful sound sync issues out by uninstalling Tune-in app and thought that was it then, but not so.  Since then, once or twice a day our 13 day old XH90 TV turns off by itself and there is also a temporary loss of sound.

I also noticed the other night the sound bar just came on by itself even though the TV was turned off on standby.  What is going on with these TVs?  Why are they so buggy?  We only have it 13 days so considering bringing it back for a Samsung if these bugs aren't sorted by Sony very soon.