Dear player, if your bind showed '0', means that your previous old-character-binding has already bound for many other accounts before. Now, we have cleared the binding relation of these accounts, so the bind will back to '0'.
If you have this situation, please re-invite your old friends, and the system will show the code for corresponding rewards. But since one player can only exchange the reward for once. If you have successfully exchanged and gained the reward last time, you will be no longer able to exchange for the same reward in game. The system message will show in the game that 'one player can only exchange once at the same time'. Please kindly know that. Thank you.