MR PRICE DOUBLE CHARGED ME

On the 30/04/2021, at Mr Price Bara(Black Chain), I purchased clothes for R320 case and paid R150 towards my Mr Price account everything totaling to R470, I paid using my bank card, only to realize the cashier that was assisting me also charged the R470 on my Mr Price account, that meant they charged me double. on the 05/05/2021 when to ask them regarding the issue they said there is nothing that they can do.

I am extremely unhappy with this