I would not keep on calling. It can be annoying. However I might show up at the store during those times when the main manager or the person that does the hiring is going to be at the store, and politely ask if they are considering your application. Also be sure that your clean, well groomed are wearing clothes that look professional, in good repair, clean, and not wrinkled. P.S. Be sure your shoes are conservative, clean, polished if appropriates. Try not to show up during store busy hours, or more than twice in a single work week.