Depreciation on Mahindra Vehicles

Worst experience of my life. Bought 2nd hand Mahindra for R390000.00 cash. Within 3 days I decided I want a new Mahindra. Only did 105km with the car. Sales manager said no problem, he will give me R360 000.00 trade-in on the new Mahindra. Depreciation in 3 days (150km) R30 000.00. Car was not even registered on my name. They phoned me today 16 February 2023 to come fetch the disc and Natis. Unbelieveable. Was shocked. Contacted Mahindra SA - they do not have a pre-owned programme. Dealers manage the program at their discretion. Still can't believe what happened. And the sad part is....no one have your back.