Many thanks for your replies. I did wonder about the SIM card sensitivity, maybe something to do with "terrorists" sending SIM cards from easy to buy places to difficult countries to do some bad stuff, but perhaps an over-reaction.
Mail is out of the question to South Africa, as most of the Express delivery takes over a month, and is unlikely to ever arrive. My Christmas cards for 2018 sent from UK arrived early March.
As a cautionary tale, I bought a cheap phone in Cape Town and boy is it cheaply made. Chinese economics at its best. It is slow, runs out of battery in half a day and has a touch screen that doesn't.
Time to tie my phone to a limb when abroad I fear, or have it surgically attached...