Can't activate bonus content on Need For Speed Shift 2: Unleashed Limited Edition

I bought a copy of Need For Speed Shift 2: Unleashed Limited Edition near the middle of last year. When I created an origin account and activated the key back then I was able to activate the bonus content (a few cars mostly). But a few months ago I did a system reinstall and have reinstalled it today, but I have not only failed to log into Autolog, but it refuses to activate bonus content. At first it seemed to be that I didn't have the password, so I took the steps to reset my Origin password, but to no avail. It still refuses to log in as it says that "the key '(product key)' had been activated in another account and cannot be activated. I really want to activate the bonus content now, and I can't work out what else to do, If someone could help me with this, I'd really, truly appreciate it, thanks.