Customer service told me twice my email address was successfully updated but When I try to log in it's still my old email address

I need to update my email address.

I have called customer service numerous different times and the last time I talked to some1 they told me My email address had been updated but yet Every time I try to log in to my AT&T account to check My phone plan and all the lines I have connected to my plan it still shows my old email address that I no longer have access to. I need to update my email address as soon as possible I need this done immediately. Thank you for your time and I really appreciate it. I really need this done within the hour really the next half hour if at all possible please and thank you.