Hey there
If the update isn't working over the air then SmartSwitch is your next best option. Do you have a friend who you could ask so that you can plug in?
Details on Customer Service numbers for your region can be found at
www.samsung.com and go to bottom of page for Contact Us.
I am not employed by Samsung nor do I receive any remuneration as a Samsung Members Star.
My device is an S25 Ultra.