okay... not having much knowledge on that particular phone. does it even detect the card ? you have tried copying 1 song to the device ? (if that is even possible).. sounds like the CSR didn't know all that much about it either and tried to get you off the phone by telling some bs.
have you posted this matter on HowardForums ? they have a LG section:
http://www.howardforums.com/forumdisplay.php?f=116