Removing degraded window tinting

[Bulandgoose]

MyAU Fairmont has the usual problem with the rear window tinting going opaque/purple.

I've read that you can remove the film by softening it with ammonia and using a steam cleaner.

The steam worked with all the door windows, allowing me to peel the film off, but the adhesive remains behind. Ammonia starts to take it off, but it's an extremely slow process needing a lot of elbow grease. Is there a faster way?

The tinting on the rear window seems to be completely different, more like some sort of jelly applied to the glass. Ammonia has taken some of it off, and at least I can see out of it now, but getting the rest of it off is another uphill battle.

Any ideas?