Mass Effect 3 multi player online pass

Hi,

I bought ME3 second hand a while back but I've only just wanted to try multiplayer. There was a code in the box I bought but I think it's already been used (my xbox said something like that) I was wondering is there anything I can do to renew it without paying the extra money for an online pass or is buying it the only way to access multiplayer? I wasn't informed by Game when I got ME3 that I wouldn't be able to play the multiplayer without paying extra.

Thanks in advance, if anyone can help.