Audio Systems: Left front speaker cuts out on Saab., place hope, listening to the radio

Question
The left top front speaker of my 2003 Saab 9-3 cuts out at least twice a day while I'm listening to the radio. When I turn the volume up, the sound comes back into that speaker. There are five speakers in total for the front of the car, all factory parts. I have had the problem since I bought the car and the dealer has tried to fix the problem unsuccessfully. They have replaced the amp, tried to reprogram the radio and on numerous times re-soldered the connections. My warranty is running out this December and I am going nuts trying to get this problem solved in time. I don't want to tell the mechanics what to do but its frustrating that they haven't been able to fix the problem. Also the car has onstar installed, don't know if that makes a difference. I don't know what else to do, any suggestions on what the problem is? I appreciate the help.  

Answer
Devi,

 it sounds like the voice coil is loose from the speaker which causes the intermident problem , i'm really suprised they havent tried simply replacing the speaker, but maybe a friendly suggestion would get them started in the right place... hope this helps you out if you need anything else let me know

thanks

CM