Honestly, I would just repeat myself. We receive similar messages from German players almost every day and it's not related only to Vulkan Vegas, but other casinos as well.
I have a strong feeling that since you have the new gambling law in Germany, it's more and more difficult for some casinos to deliver money to their players in Germany. I would trust the casino in this case that they sent the money. Understandably, your main concern is the money you still don't have on your bank account.
First of all, I'd give it a bit more time to process the payment. If you don't receive it the next week, then Vulkan should start communicating to your bank or possibly the Vulkan's payment provider needs to start talking to them. The money won't get lost, but it could take some time to get this resolved ๐