Disgusting service from Hi Fi Corporation

I purchased a Neon iq tablet from hi fi corporation. It was a faulty unit on display which was sold to me. On numerous occasions I went to the store to complain. No joy. Service was poor. Item was still under warranty. Manager changed the charger and sent me. Back. Still no joy. Now item is out of warranty and hi fi corp manager a April informs me that I must pay upfront an amount 475 non refundable plus the cost to repair. Item cost 1400 but I must pay 475 to have item which was purchased from hi fi corp repaired plus the cost to repair. Is this fair? Where is hi fi corp's responsibility the customer? Why did sales person not tell me this upfront when I purchase the item.?Id this how company like hi fi corp do business. Even manufacturer Nu World is selling products that are poor quality. NU WORLD refuse to help.