If you notice that your SIM card is defective or if you need to change your SIM card format (Nano-SIM to Micro-SIM, for example), you simply take it to an OPT-NC branch for a free exchange.
Good to know: If you are a Mobilis subscriber (M Bundle, Prepaid Bundle, Hourly Bundle Package or Data Only Subscription), you can get your SIM card replaced in Mobilis partner stores.