Incoming calls

I recently changed from contract to prepaid, eversince the 27th of June I haven't been receiving any incoming call and my number says it doesn't exist , I've called their call center countless times all they keep on doing is telling me about call bearing, call forwarding, that they have activated my incoming call or Sim card and I should switch of my phone but up to this day am still not receiving any incoming calls I even did a swim swap dololo and they doing nothing about it.