Ill treatment

I bought electric heater at game on 03/07/18, on 10/08/2018 i took it back, hoping they could swap it because it was giving me problems, just when i got inside the shop, a lady made a joke saying yeah the winter is now over, you returning the heater now, i thought that was a joke up until I got to the counter, the woman who was assisting me said i will get a voucher so I can buy another heater but it needs to be tested first, we waited for someone to come test it but i had to buy some stuff, we left her, bought what we needed, went back to cst servcies, the lady just left like that not explaining anything to me., she spoke to her collegue saying she is taking lunch, when i ask what about my heater, she told me Zandile is taking over, so Zandile asked questions that i answered, she was talking to her collegue who was testing the heater, talking in the corner, i couldn't hear what they were saying, she then said I must leave she will phone me with the findings, i tehn received a voice mail from her saying there is nothing wrong with the heater, i must come take it, I mean I am the one who is using the heater at home, i know the issues I have with the heater, how dare she tells me it is not faulty, how difficylt it is `to swap a heater, I am soooo not happy, with game service, I believe they dn't believe me when I say my heater is faulty, I am soo infuriated, I dn't even know how to deal with this, i feel disrespected.