extextshop.com buyback@etextshopllc.com Bait & Switch--Promised Prices then Negated after receiving texts , Internet

Sent me an email soliciting books for sale.  I entered ISBN#s and got quotes.  After I sent in several books, I received an invoice that offered almost half of what I had been promised.  At that point I was told that instructor books sometimes are paid a lower amount.  After I went back through the Q&As on their website, I did find a paragraph that instructor texts did not always offer the amount promised.  So insttead of $142 as promised from the ISBN#s I had entered and what I got--it was a difference of almost half.  I was offered $86 as opposed to the $142 I'd been told before I sent the books in.  Customer service was not very helpful.  I will never sell books or recommend this online book buyer/renter to anyone.  They use the old advertising "bait and switch".  They promise you one thing and then change the offer.