scamper

I am getting an acrid smell inside the car soon after starting up, within 2-3 minutes. It is not the type of musty smell that you sometimes get when the air con hasn't been used for a while. The car has been to the dealer (twice) and to others who simply spray something into the air vents and say "run it for 10 minutes and it will be fine" which it definitely isn't. The smell irritates eyes and throat and makes even a short journey unbearable. The nearest thing I can describe is burning electric cable on an open fire. Has anyone any ideas what it could be, or what I can do next please? Thanks in anticipation.