You need to write to the Chief Officer and make a formal complaint. That department will investigate the matter and report back to you. If they do not uphold your complaint you can take it further to the Local Government Ombudsman.
They regulate Councils and consider your complaint. They offer a free, independent service and can be contacted at: www.lgo.org.uk
But they can't just turn up out of the blue and treat you in this appalling way. I am sure they need to give you notice as per your tenancy agreement.
You can also consider a Judicial Review of their decision just to turn up. This is where a High Court examines the decision of the Council to see whether it is legal and reasonable.
The Court can agree with the decision or remit it back to the Council for reconsideration
These are specialist proceedings so you may need to instruct a Solicitor to represent you.
For more information on Judicial Review please see:
But it may be that the Local Government Ombudsman deals with this for you in a quick way
Can I clarify anything for you about this today please?