Better Planet Books Did not return money when book was returned unused Internet Internet

I purchased a used book.  I then found out I was not able to take the class.  I wrote to the company immediately, but the shipment had already gone out.  They said to return it as soon as it came, and they would refund my money.  I returned it to the address they gave me.  I sent the tracking number, so I do know that they received it.  I sent 4 emails in the following month to ask when my money would be refunded.  They have not answered a single email, and they conveniently do not offer phone support.