Disgusted behaviour by manager

I recently purchased a machine that removes facial hair so they say When I went to the store they advised me it's money back guarantee however it stopped working a couple of days later I went to the verimaak store in Fourways to find that the manager is busy shopping and I need to wait I explained That the product isn't working and she said well there's nothing that she can do and that I have to keep the non working item she had to customer s****s with a pulled up face I am disgusted by the behaviour of a manager what example are you setting when I told her I will put it on social media her response was okay wow to think I grew up with their products in my house