Manually restored iPhone to ISO 9.2.1 by downloading the IPSW file from the internet. Followed instructions from the internet and all went well apart from not being able to do a restore from a previous backup. So have spent a few hours this afternoon reinstalling apps and tweaking settings not covered by iCloud. Checked with my daughter who has a iPhone 6 also, purchased a few months ago and she is not having the same problems with iOS 9.3 that I've had... strange. Anyway, happy now, despite wasting numerous hours today researching, downloading IPSW files and apps and modifying iPhone - thanks Apple... NOT