Marshalls

Two days ago I bought a beige down coat (Calvin Klein) from the Marshall's store in Pentagon City, VA. I noticed the sleeves were a little bit blueish, but I though it was just dust and I could wipe it out. The next day, I wiped the "dust" out and noticed that it was actually the internal part of the coat that had bled and stained the coat. I wouldn't be able to remove the bluish tone so I decided to return the purchase. I've never removed the tag.

When I got to the store, the Manager said my tag was not matching my receipt. I imagine he didn't want to accept the merchandise back, but instead of explaining why, he just made up an excuse.

The serial number on my tag was exactly as in my receipt, and he said that even if the numbers were matching, the issue was in the store's system. If I weren't a Data Scientist I would have believed in him, but I know how IT systems work and this is [censored]. He had no fundamental reasons to deny my return request and just created an excuse. When I tried to complain with him, he completely ignored me and there was no one else I could speak to. How can I trust Marshall's when I buy anything, if I know that if I have to return another product one day, they will simply say that my tag is not matching?
The name of the manager is Charles.