Poor customer service

So disappointed by spar Mall@55 management, the price that was advertised on the shelf was not corresponding with the one at the till. I went there with a cashier to confirm the price only to find that the merchandiser was busy fixing the prices. The cashier called the manager, when the manager came i showed him the price. He said "this is for the small one" of which i understand, i said to him "by the time i took the bigger one, the small one was not there and the bigger one was placed one where the small should be placed and it was a lot of stock". I asked him what happened to the price you is the price you pay. He responded "we dont do that here", i really ddnt like how he responded because he was so rude. What happened to consumers right? Customer service?. Then i said to him it's fine i'll take the other one, he just "okay". Not even an apology. What kind of management is this!!! M really disappointed