Poor service

My phone has been with Samsung 4 times and no one can fix the phone. Phone freezing, dropping calls, rebooting heating up. 1st repair around 18.05.2017 ref no. ********** 306. Collected the phone 25.05.2017 the same issues persist. Took the phone back 07.09.2017 ref no. JC143662. Received no response or correspondence, went to the service centre 04.10.2017, spoke to the manager who handed the phone back to me stating they did a software update. Phone came back with the same problem. Took the phone back 10.10.2017 ref no. JC144369. Again received no response or correspondence, went to the service centre which has now been closed down 03.11.2017. Phoned the customer service contact centre spoke to Tebogo, he could not help and advised that we email Samsung in regards with our issue. Sent a mail on 07.11.2017 and received no response, then mailed the CEO via the Samsung website ref no. ********** 297, still no response. Called the VOC on a few occasions and no one could help until, 15.11.2017 spoke to Shaun who assisted and had the phone delivered to me on 23.11.2017. I have asked him what repairs was done, he did not know off hand but advised he would sent the job card but did not. Tested the phone again, still having the same issues. I now asked my husband to assist, he called Shaun who advised him to get the phone to Dion Wired Nicole way which is next to the Samsung Headoffice. My Husband took the phone on 14.12.2017, the technician said he needs to do a software update as that's what the procedure says, he created a job card and updated the phone. The phone was collected and my husband took the phone to Samsung (next door) where he spoke to Sabastain (VOC ) who took the phone and job card and went to a few different technical people whom advised him that the software update will fix the phone. I used the phone since the update but the problem still exist. Can someone please assist. Regards Alisha