Customer Service call

Hey, guys. Due to my own laziness i just got myself into the following situation. I lost access to my email address permanently. News outlet that owned the domain siezed to exist a while ago but the actual mail services were provided by a different company so i still could use my email account. That unfortunatelly has changed. I still can log in but cannot recieve or send mail cause the domain finally got dissabled. And ofcause i have that email address linked to swtor account. And for some bloody reason it cant be changed without CS help. Tried creating a ticket in game but they just told me to call them cause they inly provide that kind of help over the phone. Just... why? I mean to create a ticket i need to be logged so i know the login/password and have the access to security key. Also i know the linked email address that cant be seen in the account details. But apparently its not a proof enough -_- Nope, have to make an international call...

Thats just venting. My question is for people who had to call CS. What kind of proof do they ask for? Will i be required to tell them my credentials over the phone? Cause gl me pronouncing all that correctly