Vodacom/Samsung S20 FE phone

I would like to share my ongoing battle with vodacom in Menlyn Mall close to clicks. I bought a Samsung S20FE phone which is the latest phone on contract on Friday 04 December 2020. Hardly a week having the phone, when I am texting or just making a call, the phone gets heated up. The terms and conditions I signed for indicates that should I encounter any problems within 7 (seven) calendar days, then I should take it back to the store. I took the phone back to the store. They did a software upgrade, but still the phone was giving me the same problem. I submitted the phone again to them and they took the phone to repairs and advanced Samsung repairs and yet the phone is still giving me the same problem. I spoke to the manager and I was told that him talking to me and explaining the procedure to assist me is a favour. But yet I'm expected to pay every month for a phone that is not working well. Kindly assist me