Delayed submission of form 112


i've started my articleship on aug 2011. At that time I had enrolled for bcom A& F(correspondence) at IGNOU. i've finished writing ignou exams by dec 2011 including assignments but haven't recieved degree due to minimum period. I haven't submitted form 112 as i thought it was joint program and there's no requirement to file one. I've learned recently that it is a must even for joint programs. I've seen the condonation procedure and it states that a letter stating the reasons for delay is must. Should it be written by me or my principal? Also, where does it need to be sent?