Missing FBA Shipment

So frustrating!!

Amazon have lost a shipment that was shipped via UPS, tracked and received by Amazon. After waiting 4 weeks to see the good on-sale, they have now decided the entire shipped contents are missing!

They requested the usual invoice data, and i provided everything - with their response being: the product is not named on the invoices - so case closed. I've explained i produce Gift Boxes via my registered brand, all boxes have GTIN's and an array of common products - that appear in every box. Hence why the 'invoices' do not specifically name one - out of nine plus variations!

All i get are cut & paste responses, and it is so frustrating. I've even asked for my goods to be returned, as Amazon have them (shipping data says received) and have no right to deny me my ownership. Guess what - stock cut & paste reply, taking me back to square one!

Anybody else experienced this, and how did you overcome it? How do you escalate a case to somebody with authority?