Clelo,
That's going to be in the too hard basket.
Effectively two cars need a new key and to be re-paired.
From what I was told at the Wollongong dealer, when you get a new key they have to recode the access on both keys and the car so that the missing key can't be used again. It's the security protocal.
By giving you another car's key, they have doubled the problem....
Unless it was already a 'dead' key....
There is a serial number and bar code on the side of the fob under the folding key so you'd expect a dealer should be able to identify what car it belongs to.
Good luck.
Rob.

