Problems Koeblitzer Mountain Route

Hi

I've bought the Koeblitzer Mountain Route from the download shop, but I've one problem (quite a big one). I can't use the silberlinge coaches in mint livery included since they start making a very very loud rolling noise at some speed (40 kmh usually). It is very annoying. If I keep the EFX audio activated the problem is less evident, still present (even with the train stationary), but less evident. But as soon as I close the scenario and come back to the main menu, here it comes that sound, more loud than ever. I must close the game if I want to make it stop. How can I solve this? I paid 25€ for that! And I can't even have my money back! Furthermore that route really disappointed me! The "museum railway" doesn't have platform working (I can't pick up passengers), some scenarios want assets not included, I thought they gave me also silberlinge in steinless steel body, and some scenarios are unusable because of that sound bug... Please help. Thanks