You should receive a verification email. That "no longer registered" means that it HAD one (because it has an email login) but was not verified in the required amount of time. Try emailing Jagex and explaining that it is not sending the right code?
hm... i have never seen that one before. ask him to check his email to see if it's getting re-registered to his email, and make sure you put your email in correct. That's about all i can think of hope it helps =\
If you don't get it check your junk/spam section. All my codes go there since I've set the phishing links as spam and the phish emails are similar to the codes