Refusal to replace a defective phone

I've upgraded my cell phone contract in May 2020 as my current phone at the time experienced issues with its' screen. The new phone (Samsung S10) has a connector allowing you to transfer data from the old to the new phone. I followed the instructions, but couldn't get the transfer to work on the new phone. I finally transferred the data via wifi, but this didn't go exactly as planned and a lot of data didn't transfer. I went back to the Vodacom outlet to ask for help, but they couldn't figure it out either. This was the first of a long list of issues the phone had, but since it was so random and intermittent, it was difficult to replicate to show a technician.

My first "break" came when I played a video (recorded with the new phone) and it would show random photos (also taken with the new phone) during the video. Went back to the Vodacom outlet and it had them scratching their heads. They made changes to the settings and said that I must test it over a few days.

One of the other issues I had with the phone was that it would drop my calls for no reason. To make sure it wasn't me accidentally pressing buttons with my ear, I started using the speaker phone whenever I'm on a call. This is how I noticed that the phone would drop my call when the screen goes dark after 2 minutes. I also discovered that the wifi disconnects when the screen goes off. With this I went back to the Vodacom outlet again. They agreed that it was very unusual and that they would send it in for repairs. I demanded a replacement, but they insisted on sending it in for repairs first.

In the meanwhile I phoned Vodacom Customer Care and explained to them the situation and why I wanted a replacement phone. They said that they couldn't help me and that I should sort it out with the outlet.

Weeks later my phone came back with "Software Update" as the fix. The phone no longer dropped my calls when the screen goes dark, so according to the outlet, the phone was fixed and they won't replace it.

It wasn't even a day before I started experiencing (new and old) issues such as the phone locking while I'm working on it, dropping calls and wifi connections intermittently, screen becoming non responsive etc. This got so bad that I took my old phone to the outlet for repairs December last year so I can get rid of the new phone. The old phone just got back and apparently it cannot be fixed anymore as parts are no longer available.

Despite clearly having a defective phone, the outlet simply refuses to replace it and Vodacom simply refuses to assist or intervene, so now I'm stuck with an unusable piece of junk that I still have to pay for the next 16 months.

I will not renew my contract with Vodacom again.