despite me showing him the changed Bible, the vaccination stuff, the organ transplant stuff, that they predicted so many things that never took place,
If what you are doing didn't work last time, what makes you think it'll work next time?
You are doing what the WT warned them to watch out for. Every time you talk to a Dub, you have to look for a way to get around the wall the WT built for them to hide behind, not throw yourself at it. Get clever. Learn from your mistakes.
....and if you do find a chink in their armour don't let it slip away by distracting them with other topics. Hammer away at that one chink. Make them lie. Make them explain the lie. Make them do the talking. You need them to tell you TTATT and they can't do that while you're doing all the talking.