Diabolique's suggestion should work. Just add the item you want to always throw in the bank to your Shopping List and set its value to 0 (actually, you don't have to set anything since 0 is the default). When you visit the bank, all but 0 of that item (i.e., all of that item) in your bags will get placed in the bank.
I just recently hit exalted with Lower City but the repair guy in Shatt, Lissaf. Is still reporting that I will not receive a 20% discount and does not auto repair my gear. Not sure if this is a problem in the game or the mod, any help would be appreciated. I did check wowhead and he is listed as Lower City rep.