Let the tachograph be expanded.

Hello together. I asked Mercedes to have a Tachograph installed on the factory. 1-2 hours later, not the estimate was added, but a call that it was more difficult than thought and one did not know what was needed in advance and thus also the costs could not be estimated. And it would also be unknown whether it was possible at all, whether a dummy had to be installed etc. Is there any experience? Greeting Jan