I am 17 years old and the Military Commissariat said that they would not let me go abroad, and they took me away

During martial law, conscripts between the ages of 18 and 60 are mobilized. Accordingly, they are prohibited from leaving Ukraine.

As for 17-year-old boys, they have every right to cross the border.

Complaints about the illegal actions of representatives of "military commandos", which are related to the mobilization process, can be reported verbally to the hotlines of the Ministry of Defense:

0-800-500-410, 0-800-500-442, 044-454-44-99.

Complaints about violations of Ukrainian legislation during mobilization can be submitted to the head of the Center for Manpower and Social Support (Military Committee).

If the Recruitment and Social Support Center does not respond appropriately, then illegal actions can be challenged in an administrative court. Before that, you should contact a lawyer for legal help.