Useless App

I placed an order on the App, unfortunately I had to cancel as the items were out of stock, and I only get to know after, so now the order is delivered in two parts so Part order is not cancelled, fine it was a BP machine, the machine don't work and need to be returned, I called them they say they going to send me an email, no response after 5 days, and then I sent an email still no response, i am never ordering on the App again .. my order number is ***