Rigid and unfair

I made a mistake with my booking date and as a result did not arrive to pick up the car. When I realised this mistake 2 days into the rental period I contacted them to cancel and request at least a partial refund. They refused and charged me in full for almost two weeks of rental. I have tried every avenue to ask them to consider at least a partial refund but they have refused point blank. It is clear they just care about making money no matter how unfair their policies are.