Unfiltered Story #193763

I’m the co-owner of a store that sells printer cartridges, paper and so on.
Other than originals we sell also alternative cartridges who obviously have different codes than the originals.
A customer comes inside, claiming we gave him the wrong cartridge.
Me checking the printer code: “This is the black cartridge for your printer, did you want the colors one?”
Customer: “No it isn’t. The code for black is [Our Code For Color]”
Me: “No I’m sorry. That’s the code for the color cartridge. This is the black one”
Customer: “I can’t fit it inside, the shape it’s different!”
Me: “Yes. This series have a slightly different shape for the black and colors cartridges, so it won’t fit. It seems like you tried to put the black one in the color spot.”
Customer: “No, in my printer [OCFC] is the code for the black one”
Me, showing him the computer screen: “Again I’m sorry but no. As you can see that code is only for the colors one. If you wish, you can bring your printer here and I’ll install the cartridges”
Customer: “I need to print this evening, you need to change it” (note that it was around 16:30-17:00 or 4:30-5 PM)
Me: “There is nothing wrong with the cartridge. If you bring the printer I’ll install the cartridge”
Customer, seemingly calmer: “If you are so sure I’ll try again”
Saying that he got out, but the question remain: if I’m showing you that you are wrong, it’s so difficult to admit it?