Bad Service Cell C

I have renewed my contract in February 2023 with a new Samsung Galaxy Z fold, in April 2023 the phone started to "freeze" on the open screen side. We handed the phone in at Cell C East Rand and since around the 15th of May 2023. Cell C send us a repair quotation for the amount of R20k. I have rejected the repair offer and since then can`t get my phone back from Cell C.