Left speaker crackles but it's not the speaker

[Jason4115]

this is my first time here but couldn't find answers anywhere from other sites. I have a 2015 Nissan Versa note that I installed 4 speakers into. I then went to Darells car audio to have a 4 channel amp installed for the speakers and a subwoofer with a seperate amp for that. My front left speaker will randomly crackle and when it does the sound consign out of that speaker will get louder as well. I tried swapping the speakers with another and it still crackles, even put the factory speaker back in with same results, I changed the speakers input on the amp so that the sound will come from the right side of the car but it still crackles on the left. I even unplugged the speaker from the amplifier's input so the speaker would give no sound but it still crackles. Also as a last note it will even crackle when the radio is turned off and the sound does not get louder if I rev the engine and so on, I noticed however that the left speaker is always quieter than the others but gets louder than all the speakers when it crackles. I took my car into darells 4 times already and they still haven't fixed it and I'm sick of driving an hour over there. Any way to fix it or atleast get my money back from them? I really just want them to rip the whole system out with a full refund.