it has all 3 credit agencies' information.
sometime it's a little hard to read but it contains everything you need to know. every agency has their own accound id for every single credit line you currently have or previously had.
you might want to mark the wrong info on your report and mail it along with the letter. that way, they know exactly which account to work on and remove.
make sure after appealing, you don't have any collection record or delingquencies. your scores will improve as well.
some online free credit report doesn't have everything you need.
