Stock on floor not for sale

Previous day I hand made a about 600rand sale, I returned one time the next day and they handled me we, I said it was fine there is goods I needed to get for baby shower so didn’t need cash back but would get goods and pay in difference. I spend about and hour in store choosing the iteams I wanted and one of these iteams I had seen the previous day, a dummy with a mustache, I took it with about 300rands additional goods to pay for. Waiting in que to get to the till and have the lady say I can’t buy this item because it is only on sale next week, no mater what I asked it became unpleasant she actually was rude and I got anoid because I came back for this dummy and if it is on the floor surely they should be able to get it cleared as I was purchasing more items, I left all the goods and took my cash back. I find it pathetic that they made an error in putting it out I saw it and really wanted it for my gift. If it was not put out I would not have known any better. Very frustrating and would rather shop elsewhere just on principle where there is good customer service and the staff know how to communicate appropriately with clients.