Discount Radiator Covers How Can I Resolve Dispute With A Car Dealer?

How can I resolve dispute with a car dealer? - discount radiator covers

My car had a radiator leak and took the car to a dealer.
The dealership has found that the radiator is leaking and filling a little fluid, for which he is me, instructed over $ 100.
However, as I have seen no improvement in my car, I brought the car a week later and asked the dealer to check the radiator again.
This time, the dealer admitted that the radiator is leaking and replaced the radiator and charged me over $ 500.
When I saw a car dealer invoice, I asked the dealer to the fees that are charged to refund the liquid, but only gave me from a good distance.
Can I obtain a full refund of the rate of fluid?

So when I bought the car from a private individual, who six months ago I had the dealer check the car for $ 100 and was assured that if the car is under warranty.
The car dealer said that the car is under warranty because the car is less than 3 years.
However, the heater was not covered by the guarantee that the radiator is a product of the secondary market.
It seems that the radiationTor was replaced before I bought the car but the dealer did not know that by inspection.
Can I report the dealer to the cost of replacing the radiator, and it could not detect this problem during the inspection of my car?

If the recipient is responsible, please also advise how I negotiate with the dealers.

Thank you.