Rear window removal

[OlfaMan]

The ATR solution is magic stuff, but hard to get in Australia, the only place I found that sell it are a bunch of pork chops.

[Guest Good luck!]

I'm going to guess the old film was a commercial film and it had dry adhesive.  You can try citristrip or any other varnish remover but most likely if you have to go to this extreme, you're going to remove the defroster lines as it'll probably eat through the defroster lines adhesive.  Make sure you cover the heck out of the car and tell the customer you're not liable for any damage. 

[bestdealtinting]

Thanks for some useful advises, I am waiting for the car to come back and go from there will just have to tell customers all precaution  and damages might happen!! 

[Guest Jed cowler]

If you run the engine with the heated rear screen on for 5mins this normally soften s the glue enough to gently and slowly peel the film off without damaging the heated lines hope this helps 👍