Horrible service at Sandton Vodacom Repairs

Poor service at Vodacom Sandton Repairs. My phone is under warranty and they are charging me R 5 700.00 to fix a second hand phone that is still under warranty. Because there is a small chip at the corner of the phone. The phone is valued at less than R 4000.00. It a second hand iPhone 6S. Vodacom is a horrible service provider and trying to get rich fast.