The only way to get a new Parental PIN is to reset your box back to its factory settings:
Performing a factory reset on your box will delete all of your recordings.
Want to keep your recordings?
Try a Maintenance Mode Reset. It’s a few more steps, but worth it if you want to keep hold of them.
To factory reset your box:
Open the Main Menu
From Information & Reset select Factory Reset
Read the on screen warning and select Reset
Type in the numbers you see on screen to confirm you want to do a factory reset
Give your box a few minutes to reset itself and you’ll be asked go through the original setup again. This will give you the chance to set a new PIN.