So I had the same problem whilst setting up my new iMac and called Apple for help. They sorted it all out with me in about 45mins which was great. Hopefully the same will work for you.
If you have an apple id with a primary and secondary email set up this is what you can try:
1. Close iTunes and App Store
2. Delete your secondary email at appleid.apple.com (also delete it from your "Rescue Address"
3. Now use your secondary email address that you just deleted and put it in as your primary address
4. Verify the new primary email as you usually would.
5. Go to iTunes and sign in using your new primary email, the review of information should now work. Mine came up with credit card details, I selected "NONE" and continued. That was it. It worked.
6. Now, go back to your appleid.apple.com and sign in. After this change everything back to what it was originally and verify the addresses once again.
7. You should now have things back to normal and working!