Consumer Protection Act contravention

I bought a Lalela inverter on 14th January 2023 from Builders warehouse Fourways, by April the 3rd it was already broken with Fault 7 which is a fan block issue. BUILDERS refuses to refund me and their reasoning is the fan had dust. I don't have a carpet and my house is clean, therefore you sold me something that was packed with dust already because there's NO way in hell that could have happened in my CLEAN house. You disregard the consumer protection act which state that as a consumer I have the right for a refund, a replacement or repair. MY CHOICE! In this case I want my hard earned money back!!!