If I create a new account and play with the MP, am I able to use my original gamesas account to play MP once the issue has been resolved?

No.

If you use an account for online play you will have to enter your code. So it will be impossible to use it again for your original account. So don't do that. Although there have appeared a "Delete Account" option. So you can try to delete your account and create a new one. But I haven't tried it yet. It may be broken as well xDDD

Ah that svcks