they do you in on cars and lie to a person

hi 2 weeks ago i bought a second hand vito from them. i was busy so my friend looked at it and i bought it.i am in bothaville and the dealership is in potchefstroom.they brought it on the monday to have a look and i bought it on the tuesday.that day my friend filled up with diesel.that night i tried to take out the back seats but i saw the were bolted down to the floor.i went to a friend of mine and we concluded that the seats are *******.by the way the car was advertised as a mercedes benz vito crewbus.me and my friend then came to the conclusion that it was a crew cab that was altered to a bus.but is is ******* with those seats! And there is a big difference in price!i was charged r140 000.when we complained to mandy she came and look and promised to take the car back and refund the money and the diesel money,over r800.00.on monday i foned them a couple of times and eventually they paid over r140 000 but not the diesel money.when they came and fetch car on monday they promised to pay over diesel money which they did not do.i phoned today when they pick up phone they dont talk so i talk and i asked if she is going to pay diesel money and she said no.what do i do now?