You said you used the literature on the cart.
In the "Good News From God" brochure (A current favourite for JW's) Chapter 13 page 26 there is a priceless gem in the first paragraph.
I quote from Chapter 13 - p.26.
WHAT IS THE GOOD NEWS ABOUT RELIGION?
1. Is all religion good?
There are sincere people in all religions. It is good news that God sees those people and cares about them. But sadly, religion has been used for evil ends. (2 Corinthians 4: 3,4; 11: 13-15) According to news reports, some religions are even involved in terrorism, genocide, war and child abuse. How this saddens sincere believers in God!
Read Matthew 24:3-5, 11,12.
Red print highlight is mine of course.
Me to JW's on cart: "What is the good news?"
JW's: "We have a brochure about that ... here look."
You: (After listening politely - turn to P26 and read out loud the complete paragraph above) "Hmmm ... Child Abuse eh? In Australia between 1950 and 2014 1006 cases of child abuse were recorded by Jehovah's Witnesses and not one of them was reported to the police. How sad does that make sincere believers in God?"
JW's: "Err ummm apostates flounder ummm ... self justification ... "
Me: "Shame on you! Shame on Anthony Morris 3rd! Shame on Geoffrey Jackson and the whole Governing Body!" (Stand perfectly still, say nothing for ten full seconds while they stammer and fluster. Hand back the brochure and say:) "And shame on you for standing here presenting your religion as being the so called "TRUTH".
(Turn your back and walk away shaking your head.)