Apple ID and Email

I’ve had the same Apple ID since 2007 after the purchase of my 1st iPhone. A bellsouth email address.

Several years later, I lost access to this bellsouth email address.  At the time, Apple did not provide the option of to change Apple IDs but I was able to add a new email address (@Me.Com) to receive purchase receipts, confirmations, etc. 

Today, I attempted to retrieve an email for an In-App purchase and realized Receipts were no longer being sent to my @me address.  When I logged on to my Apple ID, I found email had reverted back to my original bellsouth. 

Since Apple now allows a change to ID, I deleted the Bell south and replaced with @Me. Receipts are still being sent to bellsouth.

How did my Email reset without my consent? Why are receipts still being sent to an old email after deleting? And how will Apple correct it?