Price reduction mistake

What a horrible experience....I picked up a t-shirt that was marked 50% off and brought down to R140...when I got to the counter they say it's the wrong price and it's R210...I spoke to the manager of truworths springs mall and she said there is nothing she can do about this, she will rectify the price. I asked if I can cr the t-shirt at that marked down price of R140 because it was on there already a she said no. Very shocked and dissatisfied with truworths springs mall.