It's possible the seller deals in grey imports hence the current csc and repackaged UK adapter.
Updates for such phone's can sometimes take longer.
Looking in the Samsung Members App Android 11 and Samsung One Ui 3 was sent to that phone model in December 2020 to phone's supplied by Samsung directly.
You could try removing your sim card and reinsert to see if that instigates an update or even try another different network sim card.
There are places like sammobile.com and xdadevelopers.com to look at updating software but one has to be very careful.
Disclaimer 》
Using a Custom Rom / trying to use other methods to rollback firmware can bring about an unstable phone or it may not work properly if the process glitches or the wrong Rom is used. It may stop Samsung Pay from working if the procedure trips your Knox Counter.A person takes full responsibility if they perform this process and do so at their own informed decision. Again the process may trip Knox and may affect the Samsung Warranty. Samsung could levy a charge to put this right or deny support.
That or if you have one local visit a Samsung Experience Store or Samsung Service Centre to see if they can help or alternatively keep periodically checking your phone's software update section and turn on Auto Update over Wi-Fi in your phone's settings.
Daily Driver > Samsung Galaxy s²⁵ Ultra 512Gb ~ Titanium Black.
The advice I offer is my own and does not represent Samsung’s position.
I'm here to help. " This is the way. "
