Replying to UPS BONED me.

so i shipped a touchscreen headunit that i sold on ebay through a mail store in town. they never offered me insurance and apparently didnt package it well enough so the screen was shattered by the time i arrived. the mail store is refusing to pay because i didnt buy insurance...(which is $1 for every 100 dollars insured... if they think i wouldnt have done that on a $400 dollar head unit theyre nuts) and ups is refusing to help me out because they didnt pack it. anyone have any ideas?