Attitude from manger

I bought a new kettle in January 2018 from Shoprite Oudtshoorn, end beginning 2018 the kettle could not switch , so i took it back to the store for a exchange. I had no problem with it then, but at the time of the exchange the supervisor took my slip, so i told no i have to keep the slip as the kettle was under guarantee for a full year, which means if it break again before Jan 2019 i can exchange it again, she no thats not how it works so i left the store pist!! I called the manager on Friday i said he want proof that i bought the kettle in Jan and i should identify the person that did the exhange!!! I obviously dont have any proof as your supervisor took myself, this guy practically called me a **** im not very happy with th kind of treatment i got, i spend thousands of rands everymonth at Shoprite oudtshoorn and thats how i get treated!! Not cool