Vettel helmet does not exist in-game yet mate.
And mods cannot help you if you have been scammed. You need to be more careful.
The rules in this forum are that you may not accuse someone publicly of scamming (even if it is true) and that you make a complaint in the 'grief reporting' section on the PSN homepage.
That is no help to you either since the gifting option is GT5 was not designed for trading.... only gifting. Therefore not completing a trade is not breaking any terms and conditions of this site, PSN, or GT5 use policies.
I say investigate the person you are to be trading with. Search their name in the traders reputation thread. Look at their profile page, and enjoy your future successful trades.