Defy fridge from fair price mankweng

Bought a fridge on Tuesday, Wednesday it was delivered, Thursday called the store it was not working they said we need to come in store. My mom went on Friday they refuse to change it. They don't want to take responsibility for exchanging it but putting a blame on defy. The say they need defy to authorize for exchange but when I call defy, defy says the store placed a call for technician to come and check it first. My question is why don't they change it cause it's still new and they will deal with defy on their own. Why must we wait for a defy technician ? Fair price is not fair what you doing to my mom she trusted the store and choose the defy brand. The store needs to take responsibility, the worst part is if I call the store the staff does not want to tell me their names.