I always ask for supervisor because supervisor have more " power" and can do more thing than employer if supervisor say not ask for their supervisor, most of the time their supervisor don't work in front line and don't deal with people because they seat in office and count money

but still you can ask to speak with them they refuse and saying I may help you in this situation and I am sure we can find solution.. because supervisor don't want to get warming from their boss.. you know few warming and supervisor need to find new and better job
