New mp3 jack brought static

Hi everyone. I had a local audio shop install an mp3 input jack & cable in my base model 08. Now that "AM AUX1 SAT3" channel, along with all other radio modes, sounds a constant digital interference/static noise. Kind of like when cell phones interfere with computer speakers, you know? He's only open M-F 8-5 so it's tricky for me to get there since I work those hours. Have any of you ever heard of this? thanks, J