Out of stock and no communication

My dad signed a contract for iPhone 6s Plus three weeks ago and we are still waiting for the phone. No communication from the branch to update us, we have to call them to follow up. Every time we call they give us a certain day and when we call on the day they give us another day. Either the staff are too lazy to follow up on the order properly or there is no proper system of tracking where the order is. Even the post office can track where exactly a parcel is, how difficult is it for mtn to contact their warehouse or their courier to give their customers accurate information and realistic expectations. Very poor service!! If the shortage of stock is due to the specials/ lower rates, they should have ordered more stock to anticipate higher sales volume. Or do they not have a capable person in the store to ensure adequate stock levels are maintained?! Christmas season and public holidays is not even an excuse, the contract was signed three weeks back. Do they want customers to expect poor service just because of lower prices?! I also sent a message on Facebook, no reply. First time going mtn, so disappointed. should have stayed with cellc and Vodacom.