House & home

I have a problem with House & home s manager at forest hill mall . I bought a Sony HT -m22 5.1 CH component what happened was that when the subwoofer is connected to the amplifier it display protect and switches off and I take it back to the shop their response was that I should limit the volume so I am surprised coz what's the use of having a big sound that I can't play to the full volume becose it might stop playin. All I want its that the fix it or give me the new one or different model . how can u tell a customer that he abused his radio when he is playing it in full volume plz help me coz its been over one mouth since they took in the radio the keep giving me the go around so I don't know what to do