Dissapointing Service and empty promises

2 Years ago. On the 30th of October 2015, we purchased a demo car (Kia Picanto) from Kia Silverlakes. We were assisted by the sales man Lucas Ngobeni. We received the car without the spare key and at the time we were promised that we will receive the spare key in due course. Over the past 2 years we have constantly enquired about the spare key of the car, and every time we were told by Lucas that a key will be ordered, and when we would enquire again, we were told by Lucas that the manager has left and that we would need to lodge a new complain with the new manager. They have had quite a few new managers and every time there was a new manager we had to lodge our complaint from scratch. Needless to say, 2 years later and we still don't have a spare key for the car. The irritating thing is that we had accidentally locked the key inside of the car and have had to put in a claim with our insurer just to retrieve it as it is the only set that we have. I have literally run out of options as I have even threatened them with legal action and still nothing.