Revolut Woes: Catch 22 because my phone is too old to update to latest app.

Could you do it on someone else's phone?

Sooner or later, your phone is going to stop working for other stuff too.

You borrow a more up to date handset, you insert your SIM, install Revolut, verify your number and then use it to confirm web app barcode.

Revolut is tied to your phone number, not your phone.

AFAIK you don't even have to swap SIMs once the phone number you enter in the app is correct and you can verify it using the old phone.

Correct, as far as I remember, they will ask you for your phone number you used to register, then the normal passcode.. I think they will also send a one time passcode after that to verify and that one time passcode should go to the phone number OP has.. no need to swap sim..

Just remember to log out when done with it (Or close the account as OP wanted).. That being said, I'd urge to think about close the account a bit later after receiving the fund.. wouldn't really want something to happen in between and account already closed.. that would make the situation even worse..

Also probably worth to download the statement just for record for future use.. you never know what you need it for so best just get it out of the way before account closure.