Steam says my product key is already registered

[Flyby]

to someone else. I've tried the various combinations of suggested transposing, like "B to 8", and "I to 1", but no luck. I've contacted tech support at steam but have not gotten a reply(yet) on this the second day. I know i'm the only one this has happened to, but maybe someone has an idea of how to get on with loading the sim? I bought it new from Best Buy over a year ago, but am only now getting to loading it up (new pc).
thanks
Flyby out