Shocking service from HiFi Corporation

I Purchased a Mi Box S on line in June this year and the unit started to freeze and randomly reboot, so I took it into the HiFi Corp branch in Eastgate. I requested that the unit be swapped out and they insisted that the unit be taken in for repair, upon collecting the item from repair the unit still randomly freezes and randomly reboots itself even while watching a movie or on the home screen. The Eastgate branch refuse to replace the unit and want to repair the unit even though they could not repair the unit the first time. I have ticket number *** which was assigned to me on Thursday and still no Feedback from HiFi Corporation only that they are escalating my query. Every time one goes to a shopping center you are putting yourself at risk of getting Covid, the repair should have been done correctly the first place. Please let me know how I can get a replacement unit seeing you can not repair the unit.