Can someone help me with iTunes?

I can't log in to iTunes to purchase music and I have already contacted them several times and they aren't helping. This problem started when I added a new email address to my iTunes account. When I try to log in it asks for a verification code. I then enter the correct verification code that I received and instead of logging me in to iTunes it just asks me for another code. It's driving me crazy. I will really appreciate any help anyone can give me on this. Thanks.