I understand that it must be hard to report her since she is your neighbor and you have to live next door to her for probably a long time. But, if something happens to that puppy and I didn't do anything I'm not sure I could forgive myself. If I were you I'd report it and have it removed. You could print out some information on animals and heat and have her read that too. Sounds like she doesn't have much common sense if she doesn't take it back to the neighborhood she found it in and leaves it out in the heat all day. So showing her any info. might not be of help. Do what you have to do to save its life. Good Luck and keep us posted!
Poor puppy!