Leakage

I bought a 2nd hand car in February 2021, the car have leakage that they failed to disclose, I reported it in march, they said I must bring it when it rains so that they can be able to see where the water is coming from, now when I go back they telling me that the are not going to fix it because I already finish 30days with the car, in may I had to buy a new battery because the 1 I bought with the car is not working, they said there is no refund also, and I did ask about the battery when I bought the car, they told me the battery is still okay