Hi and welcome.
First a question: Was the child(ren) in the care system before SGO was made? The answer to that changes much of what follows.
There seem to be more and more LA's looking hard at the agreements and taking the least generous interpretation.
You need first of all to commence on the formal complaint procedure. Have a look at advice sheet 25 at the bottom of page at http://www.frg.org.uk/need-help-or-advice/advice-sheets
. Please be aware that many posters here have the view that stage 1 and 2 complaints are whitewashed, and its only Stage 3, Judicial Reviews or the Ombudsman that are ever taken seriously. I think though it does vary by authority so you may well have a different experience. Ideally you need names of those that gave you the information originally, so see if you can look them up.
You do have to go through all the stages, so be prepared for it all to take months if not years.
If the child was in the care system before the SGO was made, it seems fairly clear that they have a duty to the child. It's probably better to post back that information here, (with nothing that identifies the authority, or individuals please) so that people are better able to help. Alternatively, you can call the advice line free and confidentially on 0808 801 0366.
You might also like to look at a recent thread that had a good outcome. http://www.frg.org.uk/FandFCForum/viewtopic.php?f=8&t=2947
Good luck ...... Robin