We received an sms early yesterday morning to say that we needed to submit our assignments by 20 March else we would not be able to write the exam. THIS IS INCORRECT. That is why we received the second sms as per what you are asking about.
If you have read the tut101 you will note that we do not need to submit assignments. Rather we need to notfiy via the various threads that we have completed the stages according to the schedule that Mac gave us. You should have completed Task 3A and pg 60-62 in your prescribed text book.