Cleaning white pvc window frames

[wannabefree]

What do you all use on your window frames, and how often do you do them?

To my utter amazement, vinegar doesn't work

Astonish Paste. It doesn't scratch or run ( you use a just damp cloth)
It gets all the black shoe marks off the UPVC door frame where my DS scrapes his shoe off.

Use when I can be arsed whenever it's needed