Teller refusal to sell chips-pretence of no stock

Unfortunately teller refusal to let me order chips not once but twice. Say there is no stock. Reported to management and they said they take it very seriously but nothing appears to have been done as it happened again at 18:30. First time just as they opened. How can one start the day with no stock. The second time they open until around 3am. That would mean last 6 hours no chips to sell. Very unlikely