Samsung is ignoring me and they lost my phone

We purchased a brand new S7 which would overheat and drain fast and within 1 month it had died and had to go in for repair (has never been dropped nor even scratched) I was told it would take about 10 working days maximum and I finally got it back 1.5 months later. When I got it back the issues that I had were still around but not as bad, however within a few months it died and got stuck in a bootloop if it was in charger or would not respond at all otherwise. I took it to samsung repair again and was told i would have it back in 5 - 11 working days as per Samungs TAT agreement . 14 working days later (after I had to chase around and find out why my phone was untraceable online and what the new job nr was) i was called to fetch the repaired phone. I went to collect - The shop could not find it and told me to come back next day. I did so. Next day they still couldnt find it. After going in every day last/this week, waiting many billing hours whilst ONE samsung employee was phoning trying to track where the phone is and myself spending much petrol driving there and back they are still not sure where the phone is and "cant find it anywhere". We have been promised multiple calls to sort the issue out and never received one. I am now being ignored by samsung on all platforms. This is terrible customer service for a loyal customer who has purchased over 10 Samsung products in the last few years. Very disappointed as I believed in Samsung and they have let me down massively. Not to mention of the 10 months that I have had the phone it has been in for repairs for over 2 months of that...