bad bad really bad experience

I bought a used vehicle in June by this company. The vehicle was supposeldy servised and there was even an invoice with all the parts that were replaced. Amongst those parts was the brake pads. Up until today the brake pads are making noise and I took the vehicle to them twice and they never replaced the brake pads. I have been trying to get the salesman to sort this problem out and unfortunately he is ignoring my pleads. All I wanted was for the brake pads to be replaced and I am satisfied with the state of the vehicle, I'm only unhappy with how the whole situation with the brake pads is handled.