Complex sentence: The cost of the building increased year-on-year through a combination of mismanagement, overspending and "unauthorised work", at protest was aimed at Crossland and the Mayor of Rochdale, George Leach Ashworth who oversaw the work.
Split into simpler sentences: The cost of the building increased year-on-year through a combination of mismanagement, overspending and "unauthorised work". Public protest against the high expenditure was aimed at Crossland and the Mayor of Rochdale, George Leach Ashworth, who oversaw the work.