this issue is for years now, none of the other EA games gave you a warning, they figure you figure it out
what do you expect ?

you lucky they take your money
the issue is that according to them your not supposed to have several EA accounts, so in a FOR THEM perfect world no one would have this problem, there for they will NEVER give a warning on this, and there for they dont have to help you
you can contact customer support IF YOUR LUCKY they transfer you key, but they dont have to, it all depends if you get a nice rep that is willing to help you beyond that minimum, most will tell you that they are not able to do what you ask, they have no athorisation (witch is a lie btw)
i had a similar problem before, and in nicer words they told me that im out of luck and get lost
so write nice to them, they do you a favor ... and with this i'm not kidding you !!!!