Is it a travel book run, or has anyone ever successfully dealt with it?

The short form is this: my son (in Saxony) drove too fast with my car (+26km/h). In order to save him the 3 points I used my right to refuse to testify on the hearing sheet. At some point the local KOP called and asked me strange questions, among other things whether I had a son etc. On request he also told me again that I have a right to refuse to testify if I were to incriminate relatives first degree. By the way, the police station is not a 100m vo A short time later, a letter came from the driving licence office (or similar) with the travel book requirement. Reason, among other things, significant overrun and NON-MITECTION at the identification of the driver. Costs for this: 100,- € plus 2,40€ for expenses filed objection, Reason: first time, Why did I have a right to refuse to testify and was shitted that I did not cooperate in the seizure of the perpetrator. Furthermore, I assumed to the authority that the 100,- a replacement is because the sentence would have been 100,-. Then came a letter again I should think about my contradiction, and one quoted the sentence book for refusing to testify. I did not know at all that I was in a criminal trial… *lol* Replyed again and then came the rejection of the objection, 3 pages reason and costs for the rejected objection: 100,-€ plus 2,40€ expenses. Next step would be lawsuit, but I have little bug On it…