Unfortunately, rachel is learning the hard way...as alot of us did in the beginning!!!
Only thing she can do is water changes!!!! 20 % everyday until the toxic levels have come down.
She could try to take the fish back to the shop, but if they see the fish are stressed it's unlikely they will take them back...
Possibly as well she could go to the shop and ask for a few handfuls of gravel or filter material from one of their filters. If she gets the gravel, have her get a nylon bag used for carbon. She will then stick this in her filter which will help colonize her filter quicker. If she can get filter material, have her do the same with this although she won't need to put it in a bag.
I would not suggest using these items from your tank as it is not yet fully cycled and would be of little use.
I'm glad to hear your ammonia levels are low, but you will nedd to start watching for nitrite spikes now!!
Hard way to learn a lesson, especially for the fish!!!! With Christmas just a few days off, why not suprise her with a good book on fishkeeping!!!
Better yet why not register her on the board, IT'S FREE!!!!!
We would love to have her and I'm sure we could help her become a top notch fishkeeper.
CM