Samsung Galaxy S4 Screen repair

My wife has a Galaxy Samsung S4 smart phone which incl a 2 year warrently for screen and water damage which is one of the reasons why she took the phone out. Her screen cracked 5 months ago and we have been to the Samsung repair centre in Woodlands mall in Pretoria East as well as Brooklyn mall several times to find the same excuse they do not have stock of S4 screens and it is because Samsung HO do not have stock or they have stock take and cannot sent the repair centre stock. It has been 5 months and still no screen or feedback from repair centre as to when they will get a screen to repair the phone. Why do Samsung advertise something which is untrue or they cannot commit to. This is pathetic and unacceptable