Poor service

Hello

I bought a Toyata Avanza in Mazda Hatfield 2 weeks back. On my 1st trip i makes funny noise and I drove it 2 weeks assuming that the noise with stop. Lat week I took it back to them to check what is the problem. I was told that its a gear box and since i left it on monday, No one is willing to keep me updated on what is happening and they said they cant be responsible for it. Please intervine. Mazda sold me a broken car and now they are avoiding responsibility