Mtn Westgate pathetic service

Got an updgrade a 2months ago from an iPhone to the p20 pro which came with a p8 light, 2MONTHS LATER 3 VISISTS TO THE STORE, AND MY SECOND SIM DOESN'T WORK?! The customer care agent told me that they had issued me with a faulty Sim but they ddnt have stock to replace so I waited and then went back after 2weeks and they pretend as if they have never seen me before or know what I'm talking about, however I had left my faulty Sim with one of the agents at mtn Westgate and she doesn't remember me or the Sim.... But that's not what I'm complaining about, I just want my Sim to work as I am paying a lot of money for this and I'm already regretting getting two devices because I really don't have time to be going back and forth for a ****** Sim card.... I am very disappointed that I got a device that I have never used and still paying for it.