'anne_m123' is right BUT, as many of us are aware from personal experience, 'whistle blowing' is not always subject to proper investigation and protection. Indeed, it is local authorities / employers investigating themselves - hardly independent and objective!
Again, my advice has to be to obtain as much actual evidence as possible, record it meticulously and seek to have it witnessed / corroborated.
There are indeed Complaints Procedures but these are often long-winded and almost designed to wear Complainants out. You need to insist on stated timescales for responses and if not kept to go straight to the Stage 3 process. Always useful to also keep your Elected Councillor / solicitor / Advocate aware of what you are doing throughout.
With alleged ACTUAL abuse you should make sure that you make a formal Statement to the police.