I can't see people who are calling me on iphone

From yesterday people have been calling me on my Vodacom number that was prepaid number before I took a contract, after I take a contract I asked for a sim swap to make my prepaid number be my contract number, I was surprised that I have been using this SIM card all along and I could see who was calling me, but now that is my contract number I can't see who is calling. So I took out the sim card out of iPhone thinking maybe is iPhone I put Cell C, MTN and Telkom SIM card, all of them they were showing the number when I get the call, even from the number that was not stored, I tried calling customer care but you guys don't answer the phone, I waited for more than 30 minutes on the line but no answer.<br> <br> Please fix this and if is something that I have to pay extra, pleas cancel my contract, I cannot pay for something that is supposed to be a free service.