Hi there,
It sounds to me like the HO is querying whether your course is a level 7 course. I got rejected recently in the Qualification Section because apparently I did not prove my course was level 7 (ie above bachelors degree level). My course is and I have evidence of this. I have a hearing early next year.
But if the HO are claiming the issue is not whether your course is above bachelor degree or not, but that your course is professional/vocational then it sounds like a slightly different matter. I take it you have double-checked the Policy Guidance? It states there that you have to have done a Postgraduate Diploma or have a Postgraduate Certificate or an MA or something along those lines. So was your course one of those? That's the first thing to address. If it's not, then it could be tricky.
I tell you something else which is handy to read and that is the FHEQ (Framework for Higher Education Qualifications) - google it and read their booklet. Also, contacting the following may help you:
OFQUAL (Office of the Qualifications and Examinations Regulator)
http://www.ofqual.gov.uk/
and
QAA (Quality Assurance Agency)
http://www.qaa.ac.uk/
The QAA deals with Higher Education courses and OFQUAL deals with all other courses. From the sound of what you're saying OFQUAL is the place to call first for you, in my opinion. I think the issue could be that the HO requires that you've done a level 7 course yet professional/vocational courses do NOT have levels (according to my phone conversation with OFQUAL) - this could be the issue.
However, if you have mates from the SAME course which have achieved 20 points for their Qualification Section, then surely you should be referencing this in your appeal?
Anyway, you have sought out legal aid, etc which sounds like a sensible idea to me so I'm sure you and them together will work out the right grounds to appeal on. I'm no expert but have been doing a lot of reading about qualifications, etc recently due to my own case!!
I understand what you're going through as I'm going through my own appeal process, so I wish you all the best and don't give up!
A.