Do you mean the replacement SIM card everyone will eventually get? Read this.
If not, read on:
Check if the address you provided is correct. Also verify if your name is clearly stated on your letterbox. If your address is correct, please send an email to the customer care team and we will send you a new SIM card. The first SIM card we sent you, probably got lost in the mail.
If you ordered a new SIM card (without number transfer) or a data-only SIM card, check your account to see if the registration fee has already been paid. As soon as the € 15 registration fee has been paid, the SIM card will automatically be shipped. If you chose a SIM card with a subcription, the fee is paid during the activation.