You can check which CSC you're in, but that's besides the point. If someone changed the CSC code for their region, you are stuck on that last update. Changing the CSC breaks OTA updates. You can take the phone to Samsung or Repair Shop (make sure they are trustworthy) Or you can check yourself using Samfw tools.
Hi there try these steps settings > account > reset please make sure you backup your data then restore your data & check software update. This method should help you
