האם ניתן לעקל רכב הרשום על שם צד ג' במקרה של איחוד תיקים?

(in English because no Hebrew letters on this laptop). Hi, my father is on ``ihud tikim`` for 2 years and pays monthly without problems.  I have a car on my name. My father works from 05:30 to 15:00. I work from 08:30 to 18:30 plus I have “hasaot” to my work. So, I give my father the car to reach his work because I don’t need it at the morning. From the evening I take control on this car because it is my car (I pay for everything).  Recently, we got a letter that my car is “meukal” because one of the “ihud tikim” man took some spy company and recorded during 3 days that my father uses this car for his personal usage regularly. So, the questions are: (1) Is this is permitted to take MY car without any warning. (2) My father is in “ihud tikim” without payments problems. Why are these new decisions? (3) If the answers to questions are positive, what should I do to prevent them to “steal” MY car? Thank You, Meir