Out of Stock but advertising

Vodacom4U has a special on the Huawei 2 for 1 deal. I called 2 shops in our area for the deal because we need to upgrade. The shops didn’t have stock and was not sure when they would get. I called head office and asked if I could do the upgrade over the phone because of the stock issue. Thabo called me and we did the upgrade over the phone on Tuesday 9 April 2019. He said that the phones will be delivered within 7 working days. He said we will receive a sms with the waybill number. On Thursday 11 April 2019 we called and asked why we didn’t received the waybill number yet. They said no we must just wait we will receive the sms soon. Friday 10 April 2019 I called they informed me that they have a sort of problem with the stock and not sure when they will send me the phones. I called the manager Daniel he said he will make a plan for me. On Friday afternoon the manager just let me know that they escalated the issue to Huawei. My issue is why do they advertise a product when they don’t have stock. ‭011 ********** ‬