Terrible Attitude from Manageress

We purchased two t-shirts and a button up short sleeve shirt at the Somerset West Eagle Clothing store. Total amount of our purchases R899,70; so not exactly cheap. When my partner buttoned up the shirt we realized that two of the buttons did not line up with the buttonholes. At the price we paid it is not unrealistic to expect the shirt to be of good quality. My partner returned the shirt on Wednesday to swap for one that was correct. The gentleman shop assistant checked the shirt, verifying that the buttons were not aligned and called the manageress to do the replacement. She took her time rechecking the shirt, picking it up and putting it down, then picking it up again. When my partner told her the other guy had already checked it and that he was in a hurry as he had to leave for a meeting in George, she snapped that she had to make sure (cause she does not trust her staff? Or she does not want to replace the defective shirt?). She then proceeded with the same lack of speed. When she saw my partner getting angry she got very aggressive in her tone and attitude. At the price of their clothing surely they want to retain customers? Especially those who would be return customers? Does she think we removed the buttons and then sewed them on wrong to waste our time to get the same color and size shirt? The defect was on their stock not as a result of our negligence or incorrect use. It also did not require the level of inspection she insisted on doing to waste our time. Just looking at the shirt buttoned up you can see the unalienable buttons. There is no excuse for her attitude and rudeness, we have a right as consumers to return faulty items. We were not even trying to get our money back or get something for free, we just wanted to change it. I am sure I can find another store that stocks larger sizes that will welcome our custom without treating us like that.