PUK Code

Enter an incorrect PUK 10 times and the SIM is permanently locked and cannot be unlocked. Basically, you cannot reset a PUK code.

RobertR_1616224  That is all covered in this article: https://help.smarty.co.uk/en/articles/1159752-getting-and-using-a-puk-code 

As it says, do make sure you are asking for the correct type of code first though.