contact paper question

[somavenus.livejournal.com]

I coated a letter with contact paper and now the paper is curled (the contact paper came from a roll).  I've left the letter inside a big book and have even put more weight on top of the book leaving it over night for 2 nights now with no signs of uncurling! 

Can i use an iron on the lowest heat setting with maybe a dish towel between the contact paper and the iron?? 
any other ideas on how to flatten this out??!! 

Thanks :)

(sorry txt only!)