var absenteeismsTask = AbsenteeismService.Instance.GetAbsenteeism(date.Date, date.Date);
var absencesTask = AbsenceService.Instance.GetAbsence(date.Date, date.Date);
var planningEmployeesTask = PlanningService.Instance.GetPlannedEmployees(employerCode, date);

await Task.WhenAll(absenteeismsTask, absencesTask, planningEmployeesTask);

var absenteeisms = await absenteeismsTask;
var absences = await absencesTask;
var BO_Planningemployees = await planningEmployeesTask;