I used the professionals (I got a reference from the company that put in the carpet) to come out and dye a few bleach spots in my new carpet. The work was fantastic and colorfast after a few hours. The job was a perfect match and it was quite inexpensive. I wouldn't attempt it myself. They had about five different bottles of spray dye and they just kept going over the spots mixing the the different bottles, it was kind of neat to watch and nine years later it is still good as new. Until that day, I had no idea it was even a possibility.
hth, Maribeth