Faulty sim cards

My phone was ****** and I was forced to do a sim swap on *** on *** it only started working . This was done and the sim card worked fine till *** in less than a week it is faulty. I phoned the call centre and they said the sim card was faulty. The person said I have to by another starter pack and do a sim swap again. I did it and asked for the nr to be active immediately and she told me it cant be done. This means I will be without a phone for most of the day again. I demand that cell c take there faulty cards back and replace them. You can only reach me after you fix my problem as this is my only contact nr.