i bought a car from a buy here pay here with a brake problem he said he will fix it the next day he never fix it ,i keep paying the car for 3 month

i bought a car with a 1,200 down the day that i text drive the car i told him that the car has a brake problem he said that he was goin to fix it.that it was that the car needit to be balance to take it the next day to balance the tires .i took the car to where he told me to 'the person the work on the car told me that it does not have anything to do with balance that it was a mecanical problem.i took the car back and explan to the dealer ownwer what i was told he told me not to worry that he was goin to take care of it that he thinks that is the tires and rims are big that he was goin to get me the original tires well since the first day i was stock wwith a car with no brakes .i took the car to a mecanic the mecanic said that the brake master cylinder was bad ,i told the dealer owner what the mecanic said that was wrong with the car,the part for the car was 1.200 true the toyota plus 1.000 for work ,i told the dealer owner he told me that he was goin to get the part,he never did