WRONG PRICES AND NOT ALLOWING CUSTOMERS TO EXCHANGE

I went to Pick ‘n Pay liquor at eMoyeni mall(Nelspruit. Mpumalanga) today. I wanted to buy something they told me the price, it was expensive and I decided to take something else. After some few minutes I came back and told them that they gave me a wrong price I want to exchange they refused.

My question is why are they refusing coz it’s them that told me the wrong price? And there was no price tag.