ok so this is basically a "my bro and i got in a fight and..."
so i haven't tested this yet but:
1:call blizzard's account/billing
2:say something like: "My bro and i got into a fight and he went into my email saw a beta key that i had received and he deleted the email and we recently made up and he told me" try to sound kinda sad/pissed
3: they may give you a key
once again this MIGHT NOT WORK