It happens, but my experience with various brands has been good so far.
The V sprue was/is missing in Cyber-Hobbies (Dragons) Tiger I Fehrmann Gruppe when I was about to cannibalize it and use the V-shaped air duct for my S33 build.
I guess they just could not get the sprue into the box, it´s totally jammed with parts.
Dragon Care have promised to send the missing parts, in reality that is only the track repair box and 2 brackets for the jack.
Contact their support as Rob already suggested, I have had drawings and decal sheets replaced by them before.
As Always
Boarder