Coat marked on sale for R309. 99 but I was charged R399 and they refuse to sell it at R309.99 when I return to the store

I bought a mark down coat for R309. 99 but when I checked the slip I was charged R399 I went back to the store today to buy the coat with the mark down price on the tag and they refused to do that they said the manager is on leave and the cashier from yesterday is not working today,so I can only return the coat or buy it with the price of R399 they said they can't help me because it not their fault it's the person who was putting mark down tags who tagged the coat at R309. 99. I'm so disappointed with the service received from The Fix Eshowe. It's the first time I encounter such experience with the store I believe I was supposed to pay R309. 99 the price on the tag