Game Time Card not working

I bought a game time card from amazon and it gave me an error. The next time I tried to use the code, it told me the key was already used. I am unable to find out if my EA account is linked to my swtor account, but this is the EA account that shares the same email. My username on the SWTOR account is cowsofdeath. Any help either finding the EA account linked to this or processing my game time through SWTOR would be appreciated.