John is a new procurement manager who has recently joined Smiths Facilities Management Ltd. The company provides maintenance services through the utilisation of subcontractors. It is experiencing a number of issues with its supply chain which has resulted in customer complaints, and John would like to introduce service level agreements (SLAs) to some of its key providers. Which of the following should be included?

How often the service will be provided

The procedures to be followed to resolve disputes

The qualifications needed by staff providing the service

The stock maintained by the subcontractor