Menlyn mall stuff is a bunch of ********s that took advantage of a child

My sister went to Menlyn mall to buy a laptop. Upon her arrival, she told the person by the door that's she's looking for a laptop and the person sent her to Mpho, who she told she wants a laptop and told her that they have laptops at the back, then Mpho came back with a notepad, which my sister wasn't aware of, (she told Mpho about her lack of knowledge on the difference). Upon getting to res, she set it up and realized that it has the specs of a notepad, she went to the store to return it for a laptop the next day, as the lady was assisting her, the manager said they can't because the laptop is 2nd hand already. I called the store, I have call recordings of these calls, when I called, the manager hang up upon realizing I'm calling regarding my sister and when I called again, I kept being transferred to different stuff members who kept saying they can't help, even though with each call, I specifically asked for the manager. I'm not sure if the store is trying to drag until the 7 days grace period is over or really running around, I called head office and was put on hold for over 20 mins, they said they'll escalate the matter via Facebook but they still haven't, very disappointed at the service and hope to get assistance as my sister has school work that she needs to do. I think Mpho took advantage as she saw my sister is a child.