On the wall in the Customer Service Center is posted the District Manager's phone number. Call him and complain about the lack of checkers. He will listen. Ask him for the name and number of the district vice president if that isn't also posted.
Long lines are a result of a decision made by the individual store managers to not hire enough checkers. He/she does it to increase store profits - Nothing wrong with increasing profits as long as it's not totally at the inconveinence of the customers.
Customer Service Center? That doesn't even exist at my Walmart! I've complained in the store and no one speaks english well enough to understand me, so I figure the situation is totally hopeless. The Best Buys store is almost as bad. Half the people speak english there, but no one even knows the names of their managers or where they are located. There is no such thing as good service in these large stores.