Error 8572 while trying to list products

Hello,

I’m wondering if anyone can offer some advice on my listing issue.

We are fairly new to Amazon, we have around 20 SKU’s of DAB radios listed from one brand we resell. I’m now trying to upload a variation of kettles and toasters with our own brand which were also manufactured by us. I tried to upload this batch in December 2019 and we’re still having issues, the upload was successful but saved as drafts with the following message

“You are using UPCs, EANs, ISBNs, ASINs, or JAN codes that do not match the products you are trying to list. If you believe you have reached this message in error, please contact Seller Support”

After raising a case with Amazon, I was asked to provide a few details including the below:

“A copy of a GS1 registered stating that the UPC you are using to list this product is valid and owned by you OR that you are allowed to use your own barcode to list the branded item.”

"Valid proof of Affiliation between the Brand & Barcode Owner. We would require a proof stating that the Brand “XXXXXX” is affiliated with the UPC/EAN Owner “YYYYYYY” .

The proof of affiliation can be in the form of:

Copyright
Trademark
Legal Agreement
Letter of Affiliation"

“Official websites which show the affiliation between the Brand & the owner of the barcode”

I have provided all of this proof and more but as the original case raised in December hadn’t been replied to (apart from “were researching your issue”) for so many weeks I raised a further two cases since. I’ve now provided this information to all of the cases and been advised on two that my products will be fine to upload.

"We see that both brand and manufacturer are enrolled in GTIN Authority.

Please inform that you need re-upload the products. If seller still faces GTIN authority error, do write back to us."

“We have confirmed that the Product IDs: 5060727580426, 5060727580440, 5060727580433 are valid.”

I’ve since uploaded and still having the same issue so back to square one… Has anyone ever had this problem or know a person / company who can help?

Thank you all in advance