You could always explain that it isn't an area you have experience in. However, your competitor xxx (that's been lowballing every project under the sun) happens to be a pro in that field...
OH this one is simple, and you don't even have to hit the raod to go there.... You simply tell her to shut off the main breaker, and after you hang up with her - to disconnect the phone. Because it too could be possesed...
My take on people like this is to Feed the Fear! Eventually they will get thier fill....
Mark Heller "Well - I oughta....." -Jackie Gleason