I also got a ProStreet code from GMG and was unable to activate it. So I called EA and they could not provide a code that would work nor were they able to force it on my Origin library.
They also attempted to give me NFS Carbon and that key also did not work.
So they tried to give me Crysis complete and were only able to get Crysis on my library not Warhead or Wars.
So basically the gave me a bunch of keys that I have no place to enter them. But they still IMO gave stellar support and tried to do something.
The CSR moved me up to another tier but its been 3 weeks now and I know how slow the next tier up is. Thankfully I have a shit ton of games. And GMG also refunded my purchase and gave me a $5 credit for future purchases.
All in all I am happy with what everyone tried to do. For me it was about having most of the NFS games in my Origin library sadly that didn't happen, oh well
I emailed them, they opened a ticket for me and were easily able to apply Prostreet to my account. I've had similar experiences in the past to J Seidel but they definitely are able to manually add games to the account if they know you purchased it. If you have a rep who closes your case or doesn't open a case for you, email or call again to get a new person.