SHORT-TERM INSURANCE - REMOVED MY CAR FROM THE POLICY

I have a short-term insurance with FNB. Now I wanted to do changes of removing one car and leaving another one. But guess what for the 3rd time the insurance consultant removed the wrong one. Its frustrating because this is a sensitive one. Should anything happen to the car then what? Why can't they get this right? How difficult can it be to do this necessary changes?

Or do I need to cancel this contract so that I can be taken serious?