Car with wrong service booklet!!!

Hello, I looked at a German car today and found it very nice overall. Normal mileage for the age and according to normal price. The body and the interior looked also well maintained, accident damage could not be recognized. (Year of construction 2007, 3 previous owners, 86,000 km). The service booklet was filled out and according to this also a regular maintenance in a brand – specialized workshop was carried out. The 7th sense told me during the test drive, but drive to the Fr. On the quick, he wrote down the chassis number and looked into his computer. There he found out that the car did not see the brand workshop once. In the service hewft, however, were stamps of a German brand – specialist workshop, after which the service was made there! – How can this come about? – What can be the reason for this? – It is actually in the sense of the buyer of a new car that he the inspection as long as the car warranty has been carried out in a brand – specialist workshop. – Can one buy the car anyway or should one rather leave the fingers of it? Thanks for your help.