A "stat dec" is a Statutory Declaration.

It is a legal document signed by yourself and/or anyone else who knows for a fact that when you opened the returned box it was empty.

The document simply states the facts about what happened.

Once signed this document is accepted as legal and will stand up as factual in a court of law if required.

The appropriate forms are available on line and may differ slightly from state to state.

You could take this signed stat dec and the empty box to your local Police station and ask them if you can file a police report.

If they accept that then you will get a police incident report number.

Armed with your stat dec and a police report number you are likely to get the decision overturned I would think.

If you have to file a report with the Financial Ombudsman Service (FOS) they should find in your favour.

There is a recent case on these boards where a seller was scammed out of an expensive mobile phone sold to a buyer in Canada.

They signed a stat dec and obtained a police report number and subsequently won the case with paypal.