Out of stock

I ordered a blackberry package that came with JBL headphones and speaker around 10th July 2018. I received the blackberry but was told that there was a back order on the JBL's. I was told that the JBL's should arrive the next week. I waited and called to enquire and they said the next week and so it went on. It's been almost a month now and I haven't received my devices... Why does Vodacom sell devices that they don't have.....?