Backfill the hole
First, a little trivia, mixed with a little history. Add salt for taste, if you wish.
When I got my SIN, back before I could vote, I felt that the world was finally mine. To clarify, this has nothing in common with “original sin”, but my SIN was original. Unique. A nine-digit number, embossed on a plastic card, with my full name printed nearby. Not quite a passport, but proof that the federal government admitted to my existence. I didn’t realize it was just another way to receive taxes. I felt empowered.
We were required to use the number in all sorts of important ways. At the bank. When paying taxes. Getting in to supper at the university cafeteria. You might have the same name as someone else, but your SIN was unique. We were told to keep it secret AND to tell abyone who asked what the dights might be. An identifier. Some people kept that card in safekeeping (we had to find a particular card, today). I did not go so far as to have it stencilled on a body part, but I did memorize it. When I learned that you could check if the number was valid, using a very long program on my calculator, I had to bow to the intelligence behind things. A check digit! How cool was that. And with nine dights, it shouldn’t get reused in my lifetime.
This was pre-personal-computers. Back when databases operated on mainframes.
Well, the government might know that I am unique. However, it will not assure that they can cross reference correspondence on my behalf. Send a letter (to the tax office) and you are simply trying to backfill a black hole.
I will not despair. My solution is to simply send another letter. Once the black hole is full, the next letter should sit on the top of the pile.