The problem here on Samui is the house numbering system.
It tells you when the house was built, not where it is.
You then have to go to the post office and draw a map (or two) showing where the house is.
As I said earlier, I have been receiving post OK (albeit late) for more than 20 years. So have my friends.
The problem is that the sorting office is not getting the letters to the postie. There are piles and piles of unsorted post at the sorting office.
It seems that if you are waiting for an important letter, you have to go there and find it yourself. ????