They'll probably say no, dawg, especially if you come unprepared. That's why you need to wear a full suit in to make a good impression ( I dont mean a crappy one from Jos.A.Bank or men's warehouse, your better off going to goodwill). make sure you have a Louis Vuitton briefcase, ferragamo loafers, a Rolex, and a Hermes belt, so they know you are not messing around. Act like you are there to do business at first, so you can pull out a ridiculously expensive wallet (like gucci). If they say no, tell her to fetch da vault manager, and explain the whole situation and threaten to close your account. There's nothing for them to do but say yes.
I'd never bring a weapon into a bank besides a chunk of rolls, but if you have really bad luck, I guess you can CRH al capone style.

haha