Renault Midrand negligence cost me

First time servicing my car with this specific Renault because it’s a little closer to where I stay however I regret that decision. Dropped off my car in the morning with everything in order only to get called and told that my key is not working. How is that I drove with the same key to the branch only to be called later and be informed that I’ll need to bring my spare key because the current one cannot start the key. The big shocker was being told that I will have to pay for a new key even though key got damaged or stopped working while under the branch’s care. The only issue I had with the key was the mobiliser not working but I’ve been using the key to drive the car with no issues. I’ve never been so disappointed with how a company handled an issue that shouldn’t even be my problem. Apparently to get a new key is around R3800, an amount I’m expected to pay even though the key was working fine when I had the key. I got given a number of a locksmith and the locksmith himself told me that it’s an issue that the dealership should fix and it shouldn’t be my problem. The same locksmith whose number I received from them. I’ve been advised to report this issue to the motor ombudsman because every one I’ve explained this encounter to cannot seem to comprehend how a dealership’s negligence to my property cost me.