When I make or get a call using bluetooth the other party tells me they hear their voice as an echo. I have tried turning the speaker volume down to 3-4 bars, moving the sound comming from left to right to bothe speakers, and moving the microphone to several locations in the car.

The echo is still there. Is there another trick someone has found or another microphone that will work better? Somewhere on this site I read an alternative mic caused damage to the head unit.

so far as much as I know is that you need the phone volume even lower, there is a point at which it's so low, the other party won't hear an echo. Some have played around with mic placement and speaker side with some to little effect.

You could also try de-sensitizing your mic (covering it with something), but that wil require you to talk louder to talk though it.

Where have you tried the mic, and which side did you have the audio coming out of at that time?