The buyer requested a return after having our item for a full week because the item was defective. They said because my item was defective, they had to "purchase the item from another seller" because the one we sent her had a defective pump. The item was offered by other sellers for lower prices when the request came in, so we figured she was unhappy with the price, but in order to get our item back we happily accepted the return immediately after apologizing that the item did not work. We received a different item back inside the package that the buyer sent which was supposed to include the original item they were returning. The item we received is materially different than what was originally sent. We photograph and mark with an invisible UV marker all of our items, and this item lacks the UV mark, the manufacture code does not match the original item sent, and the item includes a price sticker whereas the one we sent did not include the price. We have alerted the buyer that they "accidently" sent back the incorrect item and have instructed them that we will only issue the refund after we receive the correct item back. We have not heard back from the buyer yet about sending the correct item back. The buyer committed the old bait-and-switch tactic to return her faulty item and keep our brand new item.