discontinued product on display

My mother and I went to the Hi Shop where I was suppose to choose a phone. I instantly fell in love with the Mobi cell Pulse. My mother agreed to buy it and I asked the salesman to assist us in purchasing the phone. He went to the stock room and came back saying they had no stock. The other salesman said he could order it but he does not know how long it will take. He suggested that we buy it online. The following day mother called to order the phone but she was informed that the phone has been discontinued. I would just like to know why the phone is on display which gives the customer the idea that it is in stock and available to purchase, when it is not?