public async Task<ActionResult> SignUp(int? ID)
        {
            if (!ID.HasValue)
            {
                return RedirectToAction("Index");
            }

            using (var EM = new EventManager())
            using (var UM1 = new UserManager())
            using (var UM2 = new UserManager())
            {
                var UserClaims = new UserHelper();

                var TimeSlotTask = EM.GetEventTimeSlotByIDAsync(ID.Value);
                var DepartmentTask = UM1.GetDepartments();
                var UserTask = UM2.GetUserInfo(UserClaims.WindowsAccountName);

                await Task.WhenAll(TimeSlotTask, DepartmentTask, UserTask);

                 return View(new SignUpViewModel()
                {
                    EventTimeslot = TimeSlotTask.Result,
                    User = UserTask.Result,
                    Departments = DepartmentTask.Result
                });
            }
        }