I have no advice. I can only commiserate.
The Scholastic online book store is seriously messed up. I tried to buy books so that I could do some videotaped read-alouds for my school system that they're putting on tv. I went to Scholastic first because of the Lexile info and books are grouped by grade. Anyway, I ran into the same problems as you. I finally had to call and cancel my order because it had been over 4 weeks and nothing had happened. I am still worried that I might receive a package or have random charges.
I was very surprised by my experience. It really made them seem remarkably inept as an organization.