Sadly you are mistaken. An injunction is for a prohibitive or mandatory purpose. a writ of mandamus is not suitable for this as they are not commonly used.
You need to seek a mandatory injunction - ie to make the Council do something. This is the proper course of action.
You would need to complete forms N208:
The Court would then set the matter down for a hearing and decide whether or not to make the order to force them.
If the Court does and they refuse this is contempt of Court and the Chief Officer could be warned, fined or sent to prison.
You can also consider a Judicial Review of their refusal. This is where a High Court Judge considers the complaint and sees whether they have acted legally and reasonable.
A Court can either agree with their decision or ask them to reconsider.
For more information on that process please see:
Can I clarify anything for you about this today please?