Samsung - why does no-one respond to my emails?

I got a stunning Samsung Flip phone from the Cellucity De Waterkant branch in November 2022.

I have had to take it back twice as it had overheating issues. I eventually got it back in January - almost a month after handing it in for repairs. After a to-ing and fro-ing with the branch management, I was advised that there's nothing they can do. They can't cancel the contract. They can't replace the faulty phone.

Now I would like to know: what do I do with a brand new phone that overheats every day? I was on a video call last night and my son ask me why my new phone is overheating in his hand? This contract is costing me a lot of money and I'm not getting my money's worth!