Shocking service - they installed the wrong colour and now we must pay to install the correct colour door

We ordered a WHITE garage door from Vishal. The door is installed and after we pay (left cash), we see (on the same day of installation) the door is NOT white but cream / light green grey. It takes Vishal a few days to come back and he admits the door is not white. He now says that they will replace it with a white door but we must pay half of the new door!!!!!! WHEN WE ORDERED WHITE FROM THE START.