I made my account around 2006, and have changed my email address a couple of times. Now I can't download past purchases or even listen to the songs I purchased without my iPad prompting me to enter my old address and password for those songs.
When I went onto the Apple website and put "forgot password" for my "old accounts", of course it told me that those accounts did not exist. Of course they didn't, because they were never separate accounts like Apple claims.
What can I do about this?