Hey hun, there is a general discussion and health & beauty forum on here
but to help in this situation...
Unfortunately just because a salon is expensive, does not mean they hire high end stylists, meaning she could have just gotten out of school, she may have not went to school for long, or the product that particular salon uses may not be good quality. The best hair color hands down is Goldwell. Period. Most salons do not use this brand. But either way, okay to help with this situation did you go a lighter color or darker, or just went the same color as your non-gray hair? I ask because that does factor how the color is going to act on the gray hairs. Now, cheaper brands are not going to cover gray effectively. I am not a licensed beautician, but I do know about hair coloring, I personally do my own hair, I have been every color you can think of lol, if you want to go blonde the best bleach is Wella and can be bought at Sally's. If you are adding color to the hair (going lighter takes pigment out the hair, going darker adds) then I'd go with Goldwell. I can tell you exactly what to buy, where to buy it, how to mix it and how long to leave it on your hair if you want to do it yourself. If not find a better salon that uses Goldwell hair color. With the kind of haircolor I get (I dyed my hair back my natural color so haven't done it in months, but I did dye some long extensions my color) one tube of dye that is $8 has lasted 3 colorings on my head, and I colored the extensions and still have a little left that could be used for touch ups, the developer is $13 for the bottle and I did 5 or 6 processes with it (dyed a friends hair with the same developer, different color though) and I still have 1/4 of the bottle left. So you do the math, even buying high end, salon quality hair color, I don't pay even as much as a box kit would cost at a grocery store. And my hair has been bleached platinum blonde before and I was able to get it back my natural color easily, so if I can get good pigmentation on hair with no pigment pretty much, you should be fine using it on gray hair. Goldwell does well in covering my aunt's grays and 90% of her hair is gray, and you would never tell cause the color is so good. And btw, I haven't dyed my hair since November, and my color has not faded one bit. Of course I have not had to do touch ups cause my roots are the same color lol. Now if I went say red or darker, it would be easy to do the touch ups and doesn't take much product.
I'm sorry you had a bad experience, but before you can color again, you hair needs time to recuperate and rest. Go get a good hair mask, deep conditioner, hair restoration type treatment and do it, then wait a week and do it again. After two weeks of this and rest to the hair, then you can try dying again. Dying hair back to back can be VERY damaging, though Goldwell is a good product and actually helps the condition of the hair, it's still best to do the rest period. But either way, you will be fine, just sounds like you either went to a salon with cheap crappy product or the stylist did not know what she was doing.