I bought a Sony mobile phone in Indonesia in December 2015. It cost rp 400,000 [roughly $400] so cheaper than in Australia but quite expensive enough for me.
I was preparing for my return to Indonesia in October 2016, when Sony sent links to a free upgrade. I checked online, found good and bad comments, and also the fact that there was no going back. I was happy with the phone as it was, and didn't want to upgrade, but the demands to do it happened several times a day and I didn't want the hassle when I would be travelling and internet would often be less than satisfactory if something went wrong.
The information said the phone needed to be charged to at least 80%, so I took it to 85% to be 'safe' - famous last words.
The first upgrade failed to download, on my very good internet, and I spent 6 hours recovering my phone from an alert that happened literally every second, telling me I had to download again.
I managed to download again, and got the phone working ok, my chat backups and apps working. Switched the phone off overnight to charge it - and that was the end of my phone. It has never worked again.
I left for Indonesia the next day, and had 5 days without a phone.
A service centre [ officially approved of by Sony ] in Bali blame a battery fault, and say it is not repairable.
Not surprisingly, I find it extraordinarily hard to believe that a battery fault could occur coincidentally with a major upgrade, and not be caused by the upgrade - especially when the battery is not removable, on a phone less than 12 months old, that was working just fine till the upgrade.
After a lot of to and fro communication in this, I went on the Sony website one last time and said that my phone had died - and there has not been a message since.
So Sony products will be on my black list for a very long time to come.