Unacceptable service

On the 13th of Feb I went in to do an upgrade on my contract and upgraded to an iPhone 6 Gold and then they said they have to order and they said that I will get the phone by the next Wednesday which was the 18th of Feb, Friday they phoned me saying they don't have stock??!! This is really frustrating, how long is this going to take and how does it work that Cell C does not have stock on one of the most requested phones??!! When they need their payment they take it and I must just pay but when they need to deliver service they fail everytime??