Pay in 4

Description

I chose pay in 4 on December 2nd when I placed an order. I understood the merchandise would ship in 5 to ten business days. According to the tracking information my order still has not shipped. The merchant continues to push the ship date out. They tell me items are out of stock which was not the case when I ordered. I have asked them to send the items in stock but they will not answer that question directly. I have one payment remaining but feeling scammed. Is it normal for a merchant to wait until the final payment to ship the order? If so thus would be more like prepay over time than the loan to which the agreement describes. Has anyone else had a similar experience?