linkage was made on account creation using the email address used to the create the swtor account, if you have changed the email now used on the swtor account, it doesn't mean the ea account uses the new email address, it will still use the original email used to create the swtor account
If you login to the swtor account and go to the cartel coin tab, at the bottom of that page is a manage billing link, on the manage billing page will list the email address used on the ea account, although depending on the issue you may not be able to get to that page at moment
If all else fails you will need to call swtor support when the lines are open they can advise how to sort the account issue