how can i whiten yellowing plastic??

[wfrances]

help ,just redone bathroom.
shower switch box ,light switch box and light base which were all white plastic are yellow compared to my brilliant white ceiling,dont really want to replace them .
weve tried bleach,jif and white spirit.
anyone got any other ideas?

You don't want to hear this, but I am not aware of any way to whiten yellowing plastic other than replacing it.

Sorry!

The previous owners of our house painted over them, really badly, with gloss paint. Don't do that! We replaced them.

oh dear ,thanks anyway