A lot of players have been reset including my gf who plays on the same console as me. She was reset after playing a local game against the bots. Its not just you, if you view the Tecnical Support Forum you will see that a ton of players have been reset for no reason.... They are slowly getting back some of they're stats though. You will need to contact via Private Message Cutpurse (he's a Developer for Treyarch) regarding your stats being reset. - Include your Gamer Tag & Platform/Console
About your Codes not working you'd have to wait until you get a hold of support get that looked into, Other players have had the same issues though, they received duplicate codes from other countries.