It would not be possible to consider taking up oral coaching for one group and postal coaching for the other, if it is for the purpose of obtaining the coaching completion certificate.
First Registered for Postal Coaching
If a student has registered for postal coaching first, he/she would have paid the total fee for both the groups initially since there is no installment facility.In such a case, a student intending to take up oral coaching for one of the groups requires him/her to bear the extra expenditure for enrolling for oral coaching.
First Registered for Oral Coaching
If the oral coaching center provides for registering for each group separately, then the student might have paid the fee for only one group.Even in such a case, the postal registration for the group for which no coaching has been taken up requires the student to pay up the full fee for both the groups since no specific mention is made regarding the fee for one group.
Thus in both the cases above, it would be amounting to taking up the other form of coaching not for the purpose of obtaining the coaching completion certificate.