Pathetic Service

Received sms on my phone yesterday from Cell C stating wifi calling was activated on my account. Since then I cannot receive any calls on my phone. I can dial out but cannot receive any phone calls. I called Cell C about the problem but they said they cannot find any problem. This is really very poor service. Don't know how many calls I have not been able to receive today as a result of this.... signal in the Pretoria, Annlin area has also been going from bad to sometimes non existing...