Bad service Mica u-build nigel

Very rude service from a lady named Tania i went there to buy paint, upon my arrival at the till i received a price different to the one displayed, the displayed price barcode matched that of the paint but the price was 3 times the displayed amount, instead of the lady Tania assisting me in a polite manner she was very harsh and also lashing out at a staff member there which is obviously her colleague, the lady needs to adjust her attitude because according to the CPA I'm within my rights to demand to pay the amount displayed for an item more especially if the barcodes match.