Bad service

In January I was involved in a car accident, got a courtesy car from Europcar. My car went for repairs and took over 30 days to be ready. I wasn’t informed that I need to take the car back or extend my car hire. Now I’m getting threatening SMS’s from Europcar that I owe them R1800, and that they’ll blacklist me if I don’t pay. I’ve been calling Santam to try sort out this matter, I'm being sent from pillar to post. And they promise that a supervisor will call me back. I want to cancel my insurance ASAP