Salary forfeited on false allegation

Dear Sir/Madam, I am working as lecture in a reputed educational institute from last 4 years. Recently two students complained to principal against me that I have assigned them lower marks in their Internal and External practicals. Principal formed a discipline committee and gave his decision on the basis of findings of committee. Here are some important information for your kind pursual. 1. I don't teach the students the subject for which the students complained. 2. Principal and discipline committee didn't give me an opportunity to defend. 3. Marks which were awarded, were first division i.e. more than 60 percent. 4. Discipline committee and thus Principal held me responsible for awarding lower marks. 5. Principal issued a letter in which he has order to forfeit my 15 days salary. 6. I gave the principal my defense in writing depicting "I am not the subject teacher and I am not authorize to do so. I should not be held responsible". Thereby I requested him to revoke the orders and salary shouldn't be forfeited. I also asked him to disclose the basis of findings of the committee, i mean on what evidences the committee and he has charged me with serious allegation. 7. Principal didn't reply to written reply(my defense to issued letter). Its been 3 weeks. 8. I have been informed by HOD that principal is demanding that I (i.e me) should take my written reply back and he will compensate 15 day salary in another way or else Principal will terminate me by hook or crook. I have also heard from one of my colleague that Principal is in no mood to take his orders back. 9. I answered my HOD that I will not take letter back. If the principal seeks to close the case He should revoke his orders back in writing. Moreover, I asked my HOD what is the guarantee in believing his verbal statements? 10. My July's 15 day salary has been forfeited. I request you to kind guide me for next course of action.