Removing old plastic film remnants from wood-effect PVC door

aw

Recently moved into a house that was empty for a while. The outer doors look to be composite wood-effect doors.

The previous owners left the plastic on the doors for a long time, years it looks like and there are remnants of it attached. Glue or plastic residue.
I have attached links to a couple of (large) pictures.

I'm not sure what, if anything the previous owners did to remove it.

It's very awkward to get off. I don't want to damage the door itself.
Any suggestions as to how to go about removing it easily and without damage to the doors?
http://omg.wthax.org/7ZCapQ.jpg
http://omg.wthax.org/778Pzw.jpg

jack of all

Looks unusual but the usual DIY solution suggested for removing adhesive residue like this is gently heat up the affected area with a hair dryer then use a cloth moistened with some white spirit to dissolve the residue. Once you've removed the worst of it, wash thoroughly and maybe try a car polish like Autoglym Super Resin to even out the colour, but be very gentle and try a small inconspicuous area first.

aw

Thanks, Jack.