The guys who sent me the package and Croatia Post helpdesk have been most helpfull. this is what they've found out for me...
* the airmail option was used, so CroatiaPost expected a TimeOfArrival for such a shipment in GB to be 19/9/2008
* Croatia Post failed to recieve updated status from Royal Mail, so thats the reason they don't know any more from the time it left their hands
* There is no immediate idea of any kind of timeframe seeing as the package doesn't seem to have been registered at its destination anywhere beyond their services
* have all paprerwork, so can claim on postal insurance if needed
In otherwords, CroatiaPost confirmed it left Croatia on the 12/9/2008
* EMS Tracking number should be understood by Royal Mail, or at least they should be able to see what packages are due for the destination address.
* unable to claim any shipment in advance, but a query on the whereabouts of the package should be aimed at RoyalMail and customs service
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i'm going to occasionally persue this untill 30 days have past, then i'm going to find out what the heck happened, as if it is here and in storage somewhere, then Royalmail say they charge £5 a day storage fee! eeek!