They never gave us the correct Spare key

Bought a brand new Atos in December 2020 from lephalale. Picked up the car with spare key as is the custom when you buy a new car. Never was the spare key tested to ensure it was the correct one. Quite a few months pass and we had to use the spare key, inly to discover it was not the right key for the car. When we went back to the dealership, they "tried" to find our car's spare key. When they couldn't we were told that we had to replace the spare at our own cost.. what?! It's their mistake! They never gave us the right key from the start! They still owe us the correct key from the purchase.