DO NOT ORDER FROM THIS SITE Sites like this should be illegal. There is no way to make contact with this company other than by e-mail, which they do not respond to, nor do they update you on a placed order as to if it has been canceled or you may receive the books 3 months from now, nothing. Very disappointing.

I now know that Biggerbooks and Ecampus are the same company (same address, same customer service, same billing).  
FYI, Since Biggerbooks refuses to publish their phone number, call the Ecampus customer service number: (888-388-9909).  
I ordered 2 books, then tried to cancel the next day, via email. I cancelled because I got "upsold" to more expensive shipping than I asked for (their web interface is a real pain to navigate). They sent a cancellation email, but then I continued to get autogenerated emails saying my order would ship soon. Since I didn't have their number, I sent emails, which were ignored, and it did get shipped.  
On a positive note, the person on the phone (Ecampus) was extremely friendly, and said to refuse shipment at the post office and return the package to sender, with a refund to follow in 5 weeks.  
It has been 3 weeks so far; too early to tell if I'll get a refund.  
 
Nice or not, it was a big inconvenience.