Hi I have to request a pin code so think this is what you mean guide to explain
Hi, this guide will sort it out for you
If you enter your PIN three times incorrectly it will lock your SIM card to make sure that nobody is using your mobile without your authorization. You will then be able to unlock your device with the help of a Personal Unlocking Key - or PUK code.
THE GIFFGAFF KNOWLEDGE BASE GUIDE TO GETTING A PUK CODE AND HOW TO USE IT.https://community.giffgaff.com/t5/Solve-your-questions/I-blocked-my-SIM-what-can-I-do/ta-p/3488045
OR DIAL dial 43431 from your handset and follow the instructins and you will get your PUK code !
Good luck and hope this has helped you