Mometrix Product was not helpful, sent it back as website states if you are not please. They are saying they cannot locate my package. Beaumont Texas

I purchased the Mometrix(GACE Testing Prep) for my daughter. I inquired prior to purchasing it if this product worked. I was told yes and if I didn't want it, I could return it. When I contacted them by e-mail (as you cannot reach anyone by phone) about returning the product. I was then told I could but they would deduct the orginal shipping from my refund. So I sent the product back in good faith. Now, after 2 weeks of nothing. I contacted them again by e-mail and they cannot locate my returned package (image that). My suggestion is for no one to waste their hard earned money on this product. I think it is a scam and very unprofessional.