Trying to rob me of my device

Cell c repairs department trying to rob me of my iPhone 8, which was sent in for repairs since end October beginning of November for replacing the LCD crack, 1- it’s covered with cellsure since the day of purchase which almost 2yrs old , since my upgrade is in April 2021. 1st time it was brought back due the phone being locked and they claimed they are not able to fix if phone finder is on , they brought back the device after 2wks or so after being sent back, I sent it back mid first week November, after some time of none communication with their repairs department claiming they were on strike, they sent me a quote stating that I have to pay the excess of r25000 , when I queried it came down to r650.00 which I paid as I n my head I know that they were trying to rip me off as they only needed to fix the crack as my device was working fine, they come back telling me that they will replace with Samsung what what , since they are not able to fix it and they decided solution is to replace which I feel if it must be replaced due to that, it must be replaced with the same new device. For 2months they are busy with nothing.