Unjust limitation on stock

I have been stopping at the Richards Bay branch for 3 consecutive evenings looking for margarine that is on sale. Today I eventually found some in receiving and made my way to the till point with 24 tubs. Cashier queried with front end supervisor about stock limitation who then called floor manager who limited me to 6 items saying that's all I was allowed to take. I explained to him that there is no signage in the aisle or anywhere in-store limiting the margarine. I have seen plenty of signage in the past where items have been limited, so the store is aware of how to do this. I should not be inconvenienced at the till point when simple signage in the aisle could have sorted out a complete waste of my time. The manager said I should be fair to other customers. What other customers? Nobody else asked the staff to check for margarine in receiving or else they would have found it! Don't embarass yourselves or your customers at the till point!