Bad Service from CellC

My mum lost her phone At Mall Carnival. Since we were at the mall, we went to cell c to block the sim card. The lady told us to call customer care and block the sim. She couldn't help us Rica another sim card as we didn't have my mum's id card. I called the call Centre twice and because my mum at the age of 58 years failed the question test. thy won't block the sim. It's a pre-paid sim not a contract sim. We need help and service don't a system that can't help us. People are *****ing and getting away.