We too have exactly the same issue. Huge bill (£34000) and most of it estimates even after 1 year and the contractors coming round to clarify works.
When we ask the council for specifics and why the costs are so high we are met with guarded answers or simply silence.
Our building has been left in a shocking state of disrepair over the past few years.
When we have asked the council to be specific about the works they can’t give us answer.
We have spoken to our MP and have a councillor involved. Sadly it seems they are giving everyone the exact same treatment.
Our service charge has also increased by £200 this year but they can’t give us specifics on why.
We have asked for a detailed break down of the costs from the council for exactly one year one year now. Still haven’t for one.
This process is shocking. We are refusing to pay for anything until they can justify the works and give us full costings
Maybe a joint effort is the best course of action. They seem to be doing this to all leaseholder.