Upset Cell C customer

I upgraded my cellphone on 8 May and since then I can't receive any incoming calls. I have visited 2 different Cell C stores and they have phoned the call centre, but without any results. I phoned numerous of times and they keep telling me to do the same steps over and over. 2 Queries was logged but they close it after saying I must change the data manually to Cell C, like we have not tried that already. It is 31 May and nothing is happening. I am very frustrated and need a resolution soon.