I spoke to Samsung UK this weekend and the engineer I spoke to explained that the update should come with the 4.1.2 update, and that it should prevent further damage to the main board although it will not repair any damage that has alreasy been done.
BTW, although I said my phone died after only 30 days, I later discovered that my 3 year old had been playing with the charger and it was only 95% of the way in to the socket, so even though I thought the battery was fully charged it wasn't and when I disconnected and reconnected the charger I wasn't doing anything. So my phone is in fact perfectly ok. Now going to invest some time in looking for a backup solution.