Lewis Randburg Square does not want to Refund me

Good day, my Sister is having a serious issue with Lewis Furnisher Store at Randburg Square. She purchased a Panasonic sound system and a top loader from them, but have been facing multiple problems. The sound system stopped working after just three months, and despite multiple attempts to get it fixed or replaced, the store has failed to assist us. Furthermore, we've discovered that she was charged for additional items that we never received, including a power protector and a Donna Sleigh Bed. She paid for these items in full, but the store has not delivered them. When we visited the store to discuss these issues, we were met with unprofessional behavior and a lack of accountability. The staff seemed to dismiss our concerns, possibly due to her occupation as a cleaner and limited technical knowledge. Please assist in getting the store to take responsibility for their products and services. Specifically, she really need help in getting them to: 1. Replace or refund the faulty sound system. 2. Deliver the power protector, as she is willing to accept it. 3. Refund her for the Donna Sleigh Bed, as she never received it and do not want it.