This would take a little research on your part, but here is something you can try:
Find out all you can about another religion that has similar shunning policies, light getting brighter propaganda, and/or authoritarian, 'believe in us to be saved' leadership as the JWs.
When you go to the Hall, you can pretend that you are former member(s) of that other JW-like religion and you're going around to various churches searching for the truth. When you get into a conversation with JWs at the hall, tell them why you left your former religion using sound logic. Tell them about how controlling that former JW-like religion was, being sure, of course, to describe harmful aspects of the former religion that very closely mirrors JW practice and policy (all the while pretending you are completely oblivious to the JW worldview)!
Give them your sound reasoning as to how you discovered those practices to be unbiblical and cruel; how you realized that your former religion was discouraging you from listening to what former members had to say because they didn't want you to see through their lies and hypocrisies. Without ever being directly critical of JWs, and without coming off as being satirical or sarcastic, logically and honest-heartedly expose the errors of your former religion in such a way as to make it impossible for the JWs not to see their own organization's behavior and policies being mirrored in your former false religion. What would be super-golden, is if the Watchtower study material is of such a nature that it affords you an opportunity to share, in a brief comment, one example of the JW-mirroring, hypocrisy of your former religion and how you were able to logically refute it with scripture. That would be a TTATT WMD! (Or should that be TTATT WMA - TTATT Weapon of Mass Awakening) That ought to really get them thinking.
