Written communication provides records for future reference. This is a major advantage.

When you applied for admission to this course, how did you prove that you had successfully completed 10+2 years of schooling? By showing your Mark Sheet and School Leaving Certificates is it not? In this situation these documents which are actually written communication material between the School Board such as State Board or CBSE and you served as evidence of your educational qualifications.
In other words they legally defended your right as a candidate who has completed higher secondary level education and is eligible for college admission. Therefore written communication has the advantage of providing legal defence.
A single message can be sent through mass mailing to many people. For example once you were selected for admission to this course, MAHE sent you and all the other candidates selected for this course the same message. This is also an advantage of written communication.
Your school timetable showed you when school started in the morning and when it ended in the evening is it not? The timings were probably the same for all higher secondary students in all the sections and for other classes as well. What does this mean? The school opened at a particular time every day and it closed at a particular time in the evening. In other words the school had a policy about opening and closing everyday and this policy was uniformly applied to all classes with the help of a written communication document called time table. Therefore we can conclude that written communication has the advantage of transmitting uniform policy in any organization.

The disadvantages of written communication are that since paper is extensively used for written communication there could be problems of storage and maintenance of records.
Someone with poor writing skills could write poorly expressed messages, which are barriers to communication. When you applied for admission to MAHE you probably expected a reply within a reasonable period of time. Supposing there was a long delay you would have felt anxious and worried is it not? With written communication such unexpected delays can happen. Immediate feedback is not always possible and therefore it may take a long time to find out if a message has been received and properly understood.