C# Signature:

    [DllImport("advapi32.dll", SetLastError=true, CharSet=CharSet.Auto)]
    [return: MarshalAs(UnmanagedType.Bool)]
    public static extern bool ChangeServiceConfig2(
        IntPtr hService,
        int dwInfoLevel,
        IntPtr lpInfo);

Better C# Signature:

    [DllImport("advapi32.dll", EntryPoint = "ChangeServiceConfig")]
    [return: MarshalAs(UnmanagedType.Bool)]
    public static extern bool ChangeServiceConfigA(IntPtr hService, uint dwServiceType,
    int dwStartType, int dwErrorControl, string lpBinaryPathName, string lpLoadOrderGroup,
    string lpdwTagId, string lpDependencies, string lpServiceStartName, string lpPassword,
    string lpDisplayName);

VB Signature:

Declare Function ChangeServiceConfig2 Lib "advapi32.dll" (TODO) As TODO

User-Defined Types:

See SERVICE_FAILURE_ACTIONS structure as one possible value for lpInfo.

Alternative Managed API:

Most (but not all) functionality can be accessed using classes in the System.ServiceProcess namespace..

Notes:

See http://blogs.msdn.com/anlynes/archive/2006/07/30/683192.aspx or https://code.msdn.microsoft.com/windowsdesktop/CSWindowsServiceRecoveryPro-2147e7ac#content for details on how to call ChangeServiceConfig2.

Values for dwInfoLevel determine what structures are using for lpInfo. The possible values for this parameter can be found in WinSvc.h in the platform SDK.

1    SERVICE_CONFIG_DESCRIPTION
2    SERVICE_CONFIG_FAILURE_ACTIONS
3    SERVICE_CONFIG_DELAYED_AUTO_START_INFO
4    SERVICE_CONFIG_FAILURE_ACTIONS_FLAG
5    SERVICE_CONFIG_SERVICE_SID_INFO
6    SERVICE_CONFIG_REQUIRED_PRIVILEGES_INFO
7    SERVICE_CONFIG_PRESHUTDOWN_INFO

Not all are suported in all Windows versions see details: http://msdn.microsoft.com/en-us/library/ms681988%28v=vs.85%29.aspx

Tips & Tricks:

To open service you don't need to use Windows API (OpenSCManager() and OpenService()) use field of System.ServiceProcess.ServiceController class (ServiceController.ServiceHandle.DangerousGetHandle())

Sample Code:

    public MyServiceInstaller()
    {
        InitializeComponent();
        serviceInstaller1.Committed += new InstallEventHandler(serviceInstaller1_Committed);
    }

    void serviceInstaller1_Committed(object sender, InstallEventArgs e)
    {
        IntPtr scHandle = IntPtr.Zero;
        IntPtr svcHandle = IntPtr.Zero;
        string serviceName = "MyService";

        try
        {
        scHandle = OpenSCManager(null, null, (uint)SCM_ACCESS.SC_MANAGER_ALL_ACCESS);
        if (scHandle == IntPtr.Zero)
        {
            throw new Exception(String.Format("Error connecting to Service Control Manager. Error provided was: 0x{0:X}", Marshal.GetLastWin32Error()));
        }

        svcHandle = OpenService(scHandle, serviceName, (int)SERVICE_ACCESS.SERVICE_ALL_ACCESS);
        if (svcHandle == IntPtr.Zero)
        {
            throw new Exception(String.Format("Error opening service for modifying. Error returned was: 0x{0:X}", Marshal.GetLastWin32Error()));
        }

        SC_ACTION action = new SC_ACTION();
        action.Type = SC_ACTION_RESTART;
        action.Delay = (int)TimeSpan.FromMinutes(1).TotalMilliseconds;

        IntPtr lpsaActions = Marshal.AllocHGlobal(Marshal.SizeOf(action) * 2);
        if (lpsaActions == IntPtr.Zero)
        {
            throw new Exception(String.Format("Unable to allocate memory for service action, error was: 0x{0:X}", Marshal.GetLastWin32Error()));
        }

        Marshal.StructureToPtr(action, lpsaActions, false);

        IntPtr nextAction = (IntPtr)(lpsaActions.ToInt64() + Marshal.SizeOf(action));
        action.Type = SC_ACTION_NONE;

        Marshal.StructureToPtr(action, nextAction, false);

        SERVICE_FAILURE_ACTIONS failureActions = new SERVICE_FAILURE_ACTIONS();
        failureActions.dwResetPeriod = (int)TimeSpan.FromDays(1).TotalSeconds;
        failureActions.lpRebootMsg = "";
        failureActions.lpCommand = "";
        failureActions.cActions = 2;
        failureActions.lpsaActions = lpsaActions;

        IntPtr lpInfo = Marshal.AllocHGlobal(Marshal.SizeOf(failureActions));
        if (lpInfo == IntPtr.Zero)
        {
            Marshal.FreeHGlobal(lpsaActions);
            throw new Exception(String.Format("Unable to allocate memory, error was: 0x{0:X}", Marshal.GetLastWin32Error()));
        }

        Marshal.StructureToPtr(failureActions, lpInfo, false);

        if (!ChangeServiceConfig2(svcHandle, SERVICE_CONFIG_FAILURE_ACTIONS, lpInfo))
        {
            Marshal.FreeHGlobal(lpInfo);
            Marshal.FreeHGlobal(lpsaActions);
            throw new Exception(String.Format("Error setting service config, error was: 0x{0:X}", Marshal.GetLastWin32Error()));
        }

        Marshal.FreeHGlobal(lpInfo);
        Marshal.FreeHGlobal(lpsaActions);

        EventLog.WriteEntry("MyService", "Service modification completed");
        }
        catch (Exception ex)
        {
        EventLog.WriteEntry("MyService", ex.Message);
        }

        // Make sure to close open handles
        if (svcHandle != IntPtr.Zero)
        {
        CloseServiceHandle(svcHandle);
        }

        if (scHandle != IntPtr.Zero)
        {
        CloseServiceHandle(scHandle);
        }
    }