Hi zan, fellow SEN parent here and sorry nobody replied to your post, that's a shame and adds to your worry.
What I can tell you is that professionals can and do make malicious referrals - see this article, it's widespread across the UK: http://www.hcbgroup.com/site/blog/education_blog/parents-face-new-obstacle-for-sen-support
You have been treated appallingly. Have you sought advocacy?
They have to ask consent for accessing yours or your children's files under Data Protection Act 1998.
You can request copies of the referral, any meeting minutes and any reports so that you can respond in writing. If they are conducting a Section 47 and did so without contacting the family they are acting illegally:
https://suesspiciousminds.com/tag/section-47-investigation/ (relevant judgment here: http://www.bailii.org/ew/cases/EWHC/Admin/2013/416.html)
"1) That unless there is urgency, or an assessment based on evidence that a home visit would endanger the child, it is unlawful to commence a section 47 investigation without visiting the child and speaking with the parents (that process would instead be an initial assessment)
2) Seeking background checks without parental consent would be unlawful UNLESS a legitimate s47 investigation had been formally convened and was taking place (and frankly, even then, one ought to try to get parental consent)
3) A breach of (1) or (2) above, can result in financial compensation."