Cant Supply invoice on Letterhead

[URL Removed] -- parcel stopped by customs due to request for supplier invoice. They keep on sending an invoice without any compay details on (letterhead).. Been trying since 16 April -- Live chat useless as they stop responding as soon as I copied the email by DHL --- tried 5 times today en 10 times yesterday to get a response. Emails are just plain ignored!!! I NEED AN INVOICE ON A COMPANY LOGO TO GET MY PARCEL CLEARED BY CUSTOMS!!!!!! WHAT PART DON'T YOU UNDERSTAND???