I hope the key is not broke inside of the ignition. If it is you will need more than a key replacement. But to have your key replaced all you need to do is find a local hardware store. Even with just the broke key they can do a replacement.
Car replacement keys are available from the dealership from which you purchased your car. Buying a replacement key for your car can be very expensive if your car requires a key that has a computer inside for locking and unlocking the car doors.
For an older car, a locksmith can make a copy of the existing car key to keep as a spare in case you lose your key. If you lose your key and don't have a spare, the locksmith may have to dismantle your lock in order to make a replacement key. For a 'smart key' or an electronic fob, the only option for obtaining a replacement may be going to the dealer to get one.
You can try taking the car to your local Kia dealership to get a replacement key. You can also try contacting a locksmith.
You can get the replacement key at Home Depot, is the car key # 27R
I had to buy a blank key from a daewoo dealer and then I took it into a hardware store to them to cut it for me. You can get the replacement key at Home Depot, is the car key # 27R I've just been quoted
The only place that has the tools necessary to make a replacement car key is a locksmith's shop. You will need to bring in the vehicles VIN and proof of ownership before a key can be made.
Your best bet would be to go direct to the dealer for this as going anywhere else could result in you getting a copy replacement key, which you don't want. You need to go to a dealer purely for the reason of the car and key need to be programmed to each other if it is a recent cl500.
About £120 - £150
go to Chevrolet dealer
go to a Lincoln dealer and they will use the car vin number to get a replacement key
Read the owners manual that came with the car. Key battery replacement details are in there.
You can contact your car dealer, and buy one from them.