Seems like the refurb you got might have originated from another country. Thats my best guess.
The default thing I say for this is "use the serial number to lookup the original country, then get a cheap sim of that country, put it in once a month". But that doesn't really work for you here.
To explain odin, samsung phones have a system where you connect them to a pc and you can write android back onto the device. In this case, wipe the phone clear and install the latest updated version of android. It'll probably void your warranty and it can damage the device if done wrong. But it's an emergency "everything is broken, lets wipe every last file and put fresh ones on the device".
I don't really have a good solution for you here. If the device is a uk device and you have a uk sim card, going to samsung or risking flashing it yourself might be the only option