The bank and Bezar upgrades come in alternating order. If you have an outstanding Bezar quest, you need to do that before the next Bank event can trigger. The third bank upgrade requires a trip to the Shifting Passages, which is a dungeon to the far north, and the third Bezar quest requires a trip to Hexx Ruins, which is to the south. You won't get the prompts for these quests until you have the appropriate dungeons on your map. I think that the 3rd Bezar quest also requires you to have access to Ick Swamp, even though the quest itself occurs in Hexx.