I am one of the many (yes, there are many of us now) who have lost their bank slot upgrades and the items contained in those slots. After being told by a Live Customer Support rep that the matter will be look at by those who could fix the problem and that it shouldn't too very long, I am still waiting for any more information from TESO about the matter.
Now my problem didn't happen until late Friday evening (PST), but I have read that there are those with the problem since April 1st. Now it's been a week for those people and we just had a patch, and the problem still exists. That's a whole week for some, who, by no cause of their own, and who are now subscribed to the game, who have been forced to play with limits that are making gameplay very difficult.
Try playing without your bank. I'm not going to pay for another upgrade until I get what I already paid for back.
Fix this game breaking bug, Zenimax!