Cellphone repair before lockdownand hasnt received the phone yet

My sister took my daughters fone in to foschini the 31 Jan 2020 for repairs iv been going since feb trying to find out wat happened to her fone however no response i went back for the dnt knw hw many times n Andrew the guy that works for foschini couldnt giv me a straight answer all he said was fone was done 3 Feb however i still havent found a fone my sista went in to foschini yest 16 July spoke to manager and was told that the courier had picked up the fone by repairs bt wasnt returned to Foschini ..this morning i got a call from Andrew saying the serial number of the fone has been changed n the technician put in a different mother board which gives a different serial number bt i received an email print out from the manager at Foschini stating the serial number is still the same its been more than 5 months n only getting some kind of feedback bt its 2different stories first couriers got the blame and now this morning technicians is to blame .Ineed to know who i can contact further regarding this issue .