It's actually not broken but intentional - SE changed things that players are required to verify their billing address on your SE account before you can make any further purchases or subscriptions, as stated
here :
Apparently this change is to do with card/account fraud protections, working on the idea that a fraudulent transaction would be billed from a location (i.e. country) that is completely different to where you actually are/where the account is meant to be billed from. Unfortunately, the form is programmed in a very strict formatting that requires an address to be written in only one certain way (probably because it's actually checking to see if that address really does exist), and so players can't even get this to work a lot of the time.
Either way, there is no way around it, it's a sign of the times I'm afraid (and yes it sucks, but.. nothing can be done sadly).