poor service

Good day My mother'S fridge that she bought last year September in Thohoyandou store. Here is the case, she bought the Fridge that was priced R3999 and she was told that the fridge total installment will be R7297,89 and she has a receipt for that, however last month in May when she got a call complementing her as a customer who has not missed her installment, she then asks for the remaining balance that's when she was told that the fridge she bought was R5999 and total instalment will be R12000 and they say to her that the mistake was done by the salesperson. Please we need clarity and way forward on the matter as she is not ready to pay for the fridge that she was falsely made to buy by the salesperson. here are the details: Mrs Sivhone Makumbane Account number *** Product ID Defy C330 24BLT WD FRIDGE METALLIC DAC42

Now the store saying there is nothing they can do she needs to pay up to R12000