I've been having serious difficulty communicating to my iPhone from the car lately. The iPhone is connected to the car with an AUX input and Lightning/USB cable. I've been troubleshooting the phone and it seems to be working properly, so I suspect the car's microphone or whatever module follows that. Partly because I don't know much, I haven't found much searching this site. Seeking any input on what parts I should consider replacing, and where they are (headliner?). Many thanks.