@rom Yep. None of it makes sense.
But, apparently that is their explanation why there are SIMs that don't expire even without loading it for years.
I have a prepaid SIM card in a similar situation, although I don't have the perks, like not loading it and it won't expire (maybe I have that, but I don't want to risk it), that they cannot fix. The official reason from their engineer was, they can't find my number in their database, and how the issue I'm experiencing was because my number is in their old system that they can't migrate or search.
They actually want me to get a new SIM and give them that number so they can deactivate it. I chose to keep it.
This was years ago, I had no idea it was a serious thing until now. I thought it was just an excuse.