I’m having an issue verifying my account as every document i upload to amazon comes back as failed>

They are asking for one of the following:
Business Tax Registration
National Insurance Payment
Unique tax payer Ref
VAT registration.

I have uploaded:
Full tax return showing UTR number and National Insurance Payment
End of Tax year receiot showing UTR and NI payment.

Both were not accepted with no indication why.
A link was sent with info on what documents are needed and it basically just says UTR number.

I really need help with the exact document they need. They are too vague in the description and wont accept the docs im uploading.

Thanks