I sold 10 units on an ASIN and one of the customers reported the item "not original and counterfeit" while I received no complaint from any other buyer.

I have submitted two different invoices now with all the information the Amazon team have requested and both have been rejected and the case remains ongoing. After speaking to a customer service agent they shed some light, saying the invoices are not original and also counterfeit.

I am unsure where to go with this now as I have submitted the two invoices provided to me by my supplier, who is reputable, and they have both been rejected. Any tips would be greatly appreciated as has been ongoing for some time and it affecting my competition level.

Thanks!