UPS Imports South Africa

We had an Import from Germany in May this year, we got an email message from UPS telling us that the truck was Hijacked, send us all documentation for the claim, just to realize they are not responsible for the lost parcel. We have asked them to give us more information or a Case number so that we can put a claim in at our Marine Insurance. They gave us a Case number (No Police Station name where it was reported), no name no detail. We have a Surveyor trying to get any information, but they refuse to assist him. UPS wants us to sign a Non-Disclosure if they give us more detail, how can we not disclose this to our Insurance??? We even tried to trace the Case Number nobody can pick up the Case number so this seems like a ********** transaction, we do not even get the name or telephone number from the Head of Security of UPS. If they have nothing to hide why all the secrecy? We need anyone from UPS just to give us the real reason, was the Truck Hijacked, or were the goods ******/damaged? We had to pay our Supplier in Germany and UPS for a parcel not received.