Poor service

On the 3rd of December 2019 i took my iphone 7 back to MTN store( was assisted by Quinda at Cosmonet shop illanga in Nelspruit) since it could not start up anymore, come 22 January 2020 i decided to dial the queries line one of the consultant told me that my iphone is still under waiting for confirmation of R4000 for repairs, mind you the device is still under warranty and the fault is internal not physically but I'm expected to pay more after they made me stay 2 months without the use of the phone. I've experienced poor service. Did not even get any updates from them. Please assist.