Hello Aileen,
I have experienced and it really threw me. We had submitted all the evidence we could with the initial application and could only submit a letter for MR. But I was still swamped with doubts about letting down the lady I was supporting.
In that particular case I am pleased to say that she got an extra 7 points based on just that letter. So don't lose hope.
Catherine
Nothing on this board constitutes legal advice - always consult a professional about specific problems