Do I need both a UPC code label and FNSKU label on my products package or only one?

If only one, which one?

I have been reaching and sending this cases for brand approval with photos and I don't have clear responds....

All my hair care products have the upc code printed in the packaging and I can't re-printing them with new UPC codes... we have at leats 6000 pieces each.

When I'm trying to do the listing of my products said it doesn't match... of course the brand is hair care and a re-seller used the UPC code since my brand was sold only on B2B....

Now this re-seller is using the UPC codes for Apple watch... And amazon is not helping only rejecting the application and/ or saying that they can't help...

There is any number that I can reach out about this concern?

Hello sellers and support team,

I have an account with GS1 US and a registered company prefix for issuing UPC codes (GTINs). While trying to create new products, I discovered that another seller has been using my UPC codes to create their products.

My GS1 dashboard shows that these UPC codes are not yet active, but Amazon shows that they are being used to identify existing products on Amazon. This leads me to believe that my UPC codes were generated/sold by a 3rd party.

I've tried creating several seller support cases, and tried at least 5 different report categories in the "Report a Violation" tool https://brandregistry.amazon.com/brand/report-a-violation

About half of the ASINs that were using my UPC codes were removed by the violation report team, but half are still live on Amazon. There is no reporting tool for this specific issue, and it's been like throwing darts in the dark trying to get seller support to take action. Most violation reports come back with the reply "no action was taken because there is no violation," even though Amazon's policy regarding this issue is stated here.

Any help or insight into this issue is appreciated. And, if the support team is reading, please consider creating a reporting tool for this issue. Thank you in advance!