Verification code taking forever to arrive

I've been trying for two days now to add an email address to my AppleID and after typing the required email address in it says it's emailed a six digit code to my nominated email address.

The problem is that it takes either about 25 minutes to arrive, after which time my login session has expired and I've been kicked out of the AppleID page, or it takes about 19 hours after which time I've gone to bed, woken up, gone to work, come home, and the session has well and truly expired.

Is there any way to force the verification code to be sent as an SMS or the usual type of dialogue box which pops up as in when you're using 2FA?