Knetbooks is very good for finding textbooks at cheaper prices, especially with the free shipping even with the return. Just be sure to take a picture of your book's condition when it arrives; I assumed the wear and tear for the first workbook I rented was to be expected, but upon returning it I got charged full price for its condition. Just have evidence of how the book arrived, take care of it, and easy to send back.
The person was informative and clear, but the core issue was not resolved. Not the person's fault though.