Bad service

Arcon park checkers when they're busy they give people a closed sign and when you get in line you can't see if its open or closed because the customers must carry the closed sign then when you get closer to the till then they want to show you the closed sign.. When you complain about it they give you an attitude and tell you go and stand in the express tills line that doesnt even move and is so freakin long the service is slow and very bad.. Why is it when you are white you dont get the same service