Trouble exchanging factory defective kettle and a public humiliation over the defective kettle

On the 12th September 2020 I went to Clicks Port Alfred to exchange a Kambrook kettle which the lid section came off and made kettle unsafe as it refused to switch off when it boils and were still under warranty. When I tried to exchange it the lady in charge/manager were called loudly spoke so everyone around the teller could here and turned to look, her words was "Sir we do not exchange items that were forced". The kettle's lid was never forced open and no damage was present on kettle and clean so I told her no force was used and if she can find damage then I'll except it but she couldn't find damage any where so I told her I'll take legal action as if it weren't replaced as the warranty states I'm in titled to an exchange as the law states this. I wouldn't be so cross about the situation if she didn't proclaimed so loudly to the shop taking on my character and humiliating me in front of people I know that were present at the end the kettle were replaced. This is highly unprofessional and a bad character trait and really think she needs training to have a better client communication skills or if that doesn't work not in the position she works in. I buy regularly at Clicks and would be a shame if I'd go to the competition. I could ask for a public apology but will leave it.