Another suggestion: (And let me preface this with the fact that I am not a hairdresser, but I used to work at Sally Beauty and they made us get all sorts of certifications)
If she can't see you for a while, or refuses to fix it or whatever, find a semi permanent at a Beauty Supply store. Read the package, some will last 8 washings, other SAY 8 weeks. Find a brown that looks about how dark you want to go, but make sure the base color listed is ash, or green, or blue. It wont turn your hair those colors, it will just counteract the red/orange. The hair swatch sample won't look the way it will look on your head. Those swatches are done on white hair, I believe.
Again, dont do permanent, because then you are just worsening the problem. You could even check with a hairdresser if this is a good interim solution. Again, if she will fix it, take her up on it, but if you are really in a pinch. This should help.
Any hairdressers out there please feel free to comment on whether this is sound advice. I believe it is and have done it on myself, but another vote of confidence would probably be wise before pursuing!!!