Thanks to you both for your answers.
The phone belongs to an 82 year old lady and has never been Wifi connected in the three years since she got it! She was visiting us and I was trying to be helpful by setting if Wifi for her and once connected, the phone demanded to be updated!
I allowed the update to go ahead but when it had finished the phone could not see the Sim card and produced some on-screen techno-babble about missing some software. A different Sim card made no difference and the software error message was still there. ( I was not convinced that the update had gone through without problem as there was an error message at one point which seemed to clear itself.)
The best advice from the Vodaphone shop was to do a Factory Reset which I then did and the Chinese characters appeared on all screens once the reset had completed.
On the first screen there was a drop down choice box so I took a chance, pressed on the icon and lo and behold, a list of languages appeared.
Selected English and off it went.
The phone then insisted on updating two more times before it pronounced itself up to date!
The thick end of 4 hours all because I thought I would try to help an old lady!!!