Bad service

On the 28/03/2016 I went in to the store to purchase a DSTV decoder with installation, the item was on promotion so they were out of stock, so I was told I can pay for the item and when the store does receive stock they will give me a callback... The consultant told me it should take a few days, so I called 5 days later only to be told that they did not receive stock as yet, Today 08/04/2016 I called the store to find out about the decoder. And to my surprise they say to me that they sold out yesterday! I am extremely angry because nobody bothered to contact me saying that I should come in to fetch my item that I already payed for. Instead they told me that I should fetch it from another store!