Black dots and unresponsive touch

So, I repaired a customer's S5 with cracked glass and no display issue. Had it repaired looked great and worked great

. After few days the customer sends me a picture msg showing the black dots on the display and complaining about the screen being unresponsive to touch. She also mentioned they had an otterbox defender case on it which I had recommended to buy not from my store. After long text back and forth the customer mentioned that the phone was in the back pocket for some period of time while bending over. My obvious answer was to give them an example of how lcd bleeds when pressure is exerted at a localized spot or how the housing metal plate could exert pressure while bending over on the delicate display as shown here in an iphone 5s

The customer is in denial and accuses me of tricking them.

Any suggestions?