Sterns employee was rude to me even though she was the one who was wrong

Today I went to sterns with the intention of buying a watch. I Spoke to Bongi who had previously helped me with opening a new account. I told her that it had come to my attention that she did not give me vouchers. Instead of apologising, she shouted and said that I should have returned what i had bought, which was a watch and earrings. I had no idea that earrings can be returned. I purchased jewelry in the amount of R1000.00, I feel that i could have saved with that voucher. Her attitude was bad and she stopped talking to me and helped another customer. I left the shop without having bought anything because of her bad attitude