OP, I wish you well, there is some good and compassionately offered advice on here that I hope helps you, as you come across as being invested in your children, and trying hard to rebuild things moving forward. I sincerely hope that can happen.
In the wider context of the discussion that this thread has generated, I wish people would remember that each "case" is individual and specific, from the circumstances that brings contact with SS, to every aspect of the proceedings, which includes not just legalities, but personalities of all involved, alongside ideologies and the results of research that sweep people into big boxes whether they truly belong in them or not.
When the legalities aren't followed, it is often swept under the carpet, and complaints procedures are long and often circular, as no LA wants scandals all over the front page. Problematic cases are passed like hot potatoes from agency to agency, and complainers often are subtly punished for doing so.
Most people who have been involved with SS, whether having had a positive or negative experience see that child protection is necessary and vital, however, their faith in the current system to achieve that truly "in the best interests of the child" will naturally be coloured by their experience. It's good to see professionals on here agreeing it's a very mixed bag and some of the so easily dismissed "anecdotes" tally with their experiences.
The other thing that really grinds my gears is the superiority and sanctimony that oozes from some posters. The underlying attitude that if you are having difficulties with SS then it's a suitable punishment for being involved with them in the first place, yet the full circumstances of that involvement are very rarely as simple as "bad Mum", and the level of bureaucracy, scrutiny and interference in every aspect of a families life is hugely stressful and can actually help compound delicate situations in terrible ways.
In terms of the different treatment experienced by various demographics such as care leavers, those struggling with mental health issues, those in the lower socio-economic strata, there is judgement and discrimination.
Can you imagine if the McCanns had been the Bloggs, down at the local taverna knocking out karaoke classics, knocking back prosecco and "checking" on their kids, as opposed to middle class professionals enjoying tapas and a nice rioja?
If you've never been involved with SS, and certainly never had a bad experience with them, then count yourselves lucky, and stop and think before you pour scorn and judgement on those navigating it who are trying their hardest, but it is never deemed good enough for whatever reason, and believe me, often getting any sort of straight answer out of a SW is like pulling teeth when all you want to know is how best to work with them.
I went through it 30 years ago, and I've seen a few friends go through it, and nothing much has changed or improved in any direction apparently, and all the circumstances though complex were different, yet sledge hammer and nut springs to mind.