Very disappointing custom service

I bought a kettle at Pick n Pay Atteridgeville, Nkomo Village on 1st September 2023. The kettle doesn't switch itself off when the water boils, so I have to switch it off every time it boils. Today it couldnt work when I switch it on so I went and bought myself another kettle at a different store and went back to pick n Pay Atteridgeville to return it for a refund. They took the kettle and tested if it's working and it did, which was surprising to me as it couldnt work this morning, however, they could see that the lid opens up in the process of boiling the water and it also doesn't switch itself off. I spoke to a guy who claimed to be the store manager and I asked to see his badge/name tag as he wasn't wearing any, he then sent one of his colleagues to his car to get him his name tag (which felt like forever) and it was Edison, the store manager. He said they can't give me a refund but they can rather exchange and give me a new kettle. I told him I don't need a kettle as I already bought one and I opted for dog food instead, with the same value as the kettle. I told him I'm not going anywhere until they assist me and he said "we will sit together then..I can go where ever I want". How can I be forced to take something I don't need or want for that matter with my own money? The receipt doesn't have all the terms and conditions he was talking about. Is opting for dog food instead of a kettle too much to ask? I belive Its my choice as a customer to buy what I want with my own money. What I'm I supposed to do with this kettle now? I'm really disappointed with the behavior and bad customer service.