Fridge at ok port elizabeth

My mom a pensioner bought a fridge in OK pe. It was 7999 and said she wants it to be cheap and they added things that were not explained to her and the cost became 21000. My brother saw this on delivery and went inquire and told them My mother was not explained these terms and the price that is almost 3times the original 1 with unnecessary additions. They went to the shop and were thrown from pillar to post. She even asked to change and make it a lay bye because she won't afford this long term because she is 76 years now. They refused.