Chegg Book met acceptable standards but I received no payment Internet

I sold a book that was in great condition to chegg, according to their standards.  I went to check for my payment, which was linked to a Serve Card, and it said my book was donated. This book was in great condition: binder in tact, no highlighting, not a teachers edition, and all the pages were intact. I tweeted several times to Chegg, which promises to respond in 5 min, but I never got a rely. They totally just ripped me off. I read what condition the book had to be in and it met the standards. My sister swore by this company since she had rented and sold books to them before. I never received an email regarding that the book was donated or anything. Totally disappointed.