Fixing all the problems is extremely tough. I think it's important to follow certain steps. Establishing a sound governance structure to ensure plans are followed is the first step. Having a comprehensive plan containing all the projects needed to resolve the problems is also key. Focusing initially on the function responsible for ensuring employees are paid correctly and on time is another important step. Incorporating mechanisms to make the system effective and efficient would then be advisable.
I think those are also steps that have to be taken on a broader level.