Audiovox AVD300T Car DVD Player "multizone code" Questions

Can I get help to unlock the region code please? Did you check your manual? Call Panasonic for assistance? If out of warranty Panny will charge you!

...code (Region 0) is reset when the unit is turned off. It seems (and this should be verified on more players) that if you enter the number 13 instead of the zone, it makes the player multizone ...