Boss changes products prices in my hands and expect me to pay

Today I went in to the store to buy 2 pkts of hair rollers. The person in charge or boss came to me ,take the rollers and told me the price went up to R113 (1pkt) and I told him the price is R105, which I saw on the shelf. I told him he can't change it, cause that's the price I saw. He told me he can and I left the stuff on the cashier counter and walked out. Bad service, won't ever put my feet in New Look Cosmetics, Delft Mall,Cape town again.I know that if I see a price on the shelf,I should pay that price.