Bad customer service

Good day, I was at Sportscene - Irene Mall on Friday 23 April 21 to return items I bought online. Only to be told by the branch manager, the store does not do returns on items purchased online because their system cannot do it, after I argued that statement that all systems are the same for all TFG stores and then there was an excuse of a small store as some of the items they do not have in-store. I completely refused to accept it, we had an altercation. Told her I will report such behavior and I asked her for her name, her response was she does not have a name when I report her I can simply refer to her as a "branch manager". She ended up returning the items because I was persistent. Why did it have to reach an altercation and bickering for her to return the goods?