Thanks for your offer Henk, but Britain is a bit far for such a small part. I think i'll just stop complaining and scratch-up the 3 missing parts. It can't be that difficult (famous last words!). That and a lot of mud to hide the workmanship should work. It's just the inconvenience of the situation that bugs me, coming from a usually high-quality company. I think the problem is that they got cheap and combined sprues from the late Stug lll, Jagdpanzer lV/70 (the schurzen brackets were a give-away), hull top and bottom from a late Pz lV, and a sprue of new parts to complete the Stug lV appearance. Then Quality Control never actually built the model to see if this conglomeration was compatible, or even complete.
As an aside, Dragon's Pak 40 includes 3 different and very excellent muzzle brakes. As you only need one to build the gun, the remaining 2 make great replacement parts on any other 75/L43 or L48 armed vehicles. I replaced the muzzlebrake on my late Stug lll and it really makes a difference.