Hello Robert my name is ***** ***** I will help you.
Does the tenancy say you will get a reduced rent, or they will increase it once you stop work?
Are the similar properties charges a similar sum?
This is what you need to do - complain to the Chief Officer of the Council. They will investigate your complaint and get back to you.
If that office does not uphold your complaint then you can complain to the Local Government Ombudsman.
They offer a free, independent service and can investigate your complaint at: www.lgo.org.uk
Finally you can consider a Judicial Review, this is where a High Court examines the decision to see whether it is legal and reasonable.
A Court can either agree with the decision or send it back to the Council to consider again.
For more information on that process can be found at:
Can I clarify anything for you about this today please?
All the best and good luck.