Flames from my dash board????????????????

I have a problem with my 2002 skyline,when i go above 3000 revs flames come up my front window inside the car! I hav a fire extinguisher to put it out every time i do drive over 3000revs.my dash is all melted at the back.its very bad.i took it to a garage and i was told not to use the fire extinguisher and just lets the flames burn out and that its a big problem in skylines and nothing can be done?im a little confused????