Special not a special

Checkers Gezina Bought Cape point Tuna that is suppose to be on special, board does not specify which Cape poin Tuna is on special and when we pay it wasn't on special. We paid R40 a Tuna! Spoke to Manager and she just said the ones we took isn't on special. When I told her her baord doesn't show which different Tunas are on special she just said the ones we took wasn't on special. But the Tuna was on the shelf where special board was. She said it was wrongfully packed. So when I as customer take that and don't get it on special then its my fault. It isn't my fault they packed it wrongfully or there board is wrong with description. So now I must pay more because they packed it wrong and description on board doesn't specify which Cape point Tuna is on special. Very bad customer service if you tell me!