amazon asking for vat number and documents

hello. amazon have asked for my uk tax payer unique taxpayer reference which i provided several weeks ago. amazon have rejected it and asked for my vat number. I do not pay vat and i am not registered for vat. In the UK you have sell over £84000 a year to register for vat and i sell between £5000-£10000.

I am registered to sell in the UK and France. I used to use FBA but no longer have any items on it.

What could be causing this problem