i have been trying to play online on C&C3, but every time I enter my registration code that I got on the manual, it's says that it has already been used. However, I have never registered for online before, and I bought the game first hand, and I have checked that I am typing the code in correctly. Is there anything that can be done?

Also, while i am at it, I am going to buy C&C4 tommorow. if I buy it second hand, will I be able to pay online, because the code for it will have already been used.

Answer back soon please!