No-one knows what they are doing...

I have a iPhone 6, my phone could always divert & now about a 2 months ago (if not longer) it doesn't want to, I have contacted Vodacom, I have been to their branch in Uvonga as well as the 1 in Alberton City several times (unfortunetly I never took any names), everybody seems to have a different answers, I have tried all these, taking sim out, switching phone on & off, they have sent me codes nothing works, I also get told that my phone does not divert!!!! Then eventually someone told me there was something wrong with my sim, I need to do a sim swop, I have done this & still my phone does not want to divert. There is nothing wrong with my phone cos I have tried my wife's sim card and it divert's my phone. I am so frustrated cause no one knows what they hell they are doing.