Hi again Jacek
I do remember feeling exactly how you feel. I was so worried I wouldn't bond with my kittens, and having been so excited about getting them, it was a bit of a let down. We are now very bonded. Give it a few more days, in a week they'll be different kitties.
Your kittens may be missing their parents too, they looked like a lovely family. Maybe some large stuffed animals/furry hot water bottles might help? My breeder isn't breeding anymore, and my boys' mum had already gone to another home before they came to me.
Do you have something that 'smells like' their old home? My breeder sent an old towel with the kittens, and we left that in the carrier they arrived in.
If it's any help, my kittens hardly noticed when they were vaccinated. The car trip, on the other hand, all 2 minutes of it
!!
What treats are you giving them? I tried prawns, having read about it here, and they loved them. Toys with feathers on sticks/thick string are also very popular. (Thin string/elastic can be chewed through in one bite!)
Also, you need to go post in the "how did you choose your Bengal's name" thread.