Xfinity store wouldn’t let me return a cable box

Went to a physical xfinity store today and the woman working wouldn’t let me return a cable box. I went to return 2 (I have multiple in my house and trying to cut costs) and she let me return the smaller box but said my bigger box is a “main” box so I can’t return it. Has anyone run into this? I didn’t know this was a thing, I have boxes from multiple years so they all look different but most are the larger size.