I recently sold a bunch of old textbooks back. One set of books went to Textbooks.com and the other went to k12 books. Both shipped out on the same day. I received my Textbooks.com payment about two weeks after shipment. It has now been an additional two weeks, and I have not received anything from k12.com. Before I decided which buyer to use for each book, I researched the turnaround time. I knew k12 had a longer wait, but they promised enough additional payment that I was willing to wait. Now, I'm wondering how long I should wait before calling customer service. It's only $11, so I would prefer not to spend hours on the phone for no reason.
Do they have an online support system instead? It might be a few days before you hear back from them anyway, but if you don't have the time to sit on the phone, the few days may not be a big deal in comparison.
I've heard mixed reviews about K12 Books, but most of the people I know have been paid eventually. I think their customer service is faster than it is slow, so you shouldn't be stuck on the line for hours waiting for a customer service representative. Did they offer tracking on the shipping label? Or did you use your own shipping service? Perhaps they haven't even received the package of books yet, but I'd wait a couple more days before contacting them.
They must have known that I was losing my patience somehow. I got an email from them this morning. They are sending a check for $4 tomorrow. I used the free USPS boxes with their shipping label. They got charged the priority rate and deducted it from my account. I should have just used textbooks.com for all of my books.