Upgrading iCloud storage - process shuts down when going to text messages to get code

When I go to get the code to verfy payment for upgrading storage from my text messages - the icloud window closes on the iphone where I chose a new plan and logged in closes. I know this because it is on longer open when I try to go back to it to enter the code.

So by the time I get my code and go back to enter it, the whole process is shut down.

So when I relaunch it to try again to add more storage and enter the code, it says it isn't valid because now it has sent a new code. It's a bit ridiculous.

I keep getting codes but can't enter them because I have to start the order again since it shut down.

Does anyone know any other way to upgrade storage plan on iphone 13 without this circular madness please?

Thank you