New iphone 12 with factory defect

Hi! I just bought a new iPhone 12 pro last week from KPN. Apparently there was a factory defect and I had no idea about it. I assumed my phone was perfect so I threw out the box. I went back to the KPN store today and they told me that they could exchange the phone for a new one if I had the box in which the phone came with. Since I do not have the box anymore with me, they told me the only choice was to send it in for repair and not have the phone for 2 weeks. I feel very upset, sad, frustrated and tired with KPN’s response and super unhappy that I wasted a whole afternoon trying to contact customer support.  They did not tell me to keep the box. If they had, I would have kept it. I hope this message can be read to other people who are thinking about buying new iPhones at KPN. Beware of the terrible service and keep the box. I also contacted KPN through chat and asked if there was an email I could use to write my complaint or talk to someone. They said only chat and by phone. Thus, zero help. Zero.