The code that you have provided is already linked to your other Uplay account that uses the following details.
Unique Key: F3P-X8N3-HKWB-7CLY-GCYN
Game and Platform: Far Cry 3 [STEAM PC]
Username: benzmtb113
Email: benz3688_@hotmail.com
Please note that the game can only be played on the above account.
We have sent the reset password to the above email address in case you have forgotten the password to the account.