If the bank is the owner of the property because of a foreclosure then they have all the same rights of any other condo owner in your complex, including the right to rent it out. The bank also has all the same obligations as the other condo owners which is why they are paying all the fees and assessments.
I may be slightly confused by your facts, but generally a condo association would not have the right to rent a vacant condo. Your condominium bylaws should clearly spell out what the Condo association can and cannot do. If they do not address this particular situation then you may wish to consider a revision of the bylaws.