Diston Institute offers JEE coaching in Dehradun . They advertise themselves as the best institute for IIT/JEE coaching in Dehradun. Their website highlights the following aspects of their JEE coaching program:

Experienced and passionate faculty: Their faculty has over 5 years of experience in preparing students for competitive exams.
Interactive platforms: They use engaging simulations, video lectures, and quizzes to make learning more interactive and effective.
Personalized learning: They tailor study plans to your unique strengths and weaknesses.
Conceptual understanding: Their curriculum goes beyond rote memorization, emphasizing a deep understanding of fundamental principles.
Unfortunately, I couldn't find the details about the course structure or duration on their website. Here's a link to their website where you can learn more about their JEE coaching program and inquire about the course details: Diston Institute JEE Coaching