Bad service

I received a replacement device from Samsung and within 7 days the phone was over heating I called in their customer care coz I had covid and they only saw to my issue 2 months later telling me it's too late when I was waiting for them to get back to me. Kholofelo then called me and told me to give in my device for the exchange has been approved after the first diagnostic done on the phone. Which I was told to only use one app and not to use the phone with more than one app open and to only download a few apps off the play store. In my defense if I'm paying R600. 00 a month for 2 years and I have to only usey phone like this I should have the right to be refunded and buy a phone that's R100. 00 that can do so much more. After I went to give my phone in I get a call saying I used the phone right by only having one app open and only have limited apps downloaded that I can collect the phone coz there will be no exchange. Now cell c can't take the phone back coz Samsung did a swop on the first device being an issue. And Samsung does not want to give me back the original phone to cancel the contract nor do they want to replace their broken device.