getting an int to — after an action

[xnaLearner]

so in my person table...I have Id, Name & HolidaysRemaining. Its for a holiday booking application, and atm when a user selects dates from a calendar and clicks the button, each date selected will be stored in the DB, I am trying to minus the holidays remaining by 1, as each holiday is booked, but it doesn't seem to be picking up.

//listHolidays in correct format dd/mm/yy
[HttpPost]
public ActionResult listHolidays(Holiday holiday, Person person, int? PersonId, string HolidayDate, string endDate, string AlreadyExists)
{
//int holidaysRemaining = 20;
//person.HolidaysRemaining = holidaysRemaining;

        DateTime startDates = Convert.ToDateTime(HolidayDate);
        DateTime endDates = Convert.ToDateTime(endDate);

        while (startDates <= endDates)
        {
            if (startDates.DayOfWeek != DayOfWeek.Saturday && startDates.DayOfWeek != DayOfWeek.Sunday)
            {                 
                    //if user selects Holiday that already exists, wont add it to Db
                    //gets string, and uses the previously converted to dateTime 'startDate'
                    //id so only applies to person creating holidays
                    ViewBag.CantDuplicateHolidays = String.IsNullOrEmpty(AlreadyExists) ? "date" : "";
                    var dates = from d in db.Holidays
                    where d.HolidayDate == startDates && d.PersonId == PersonId
                    select d;

                    // <= 0..so if holiday does not already exist
                    if (dates.Count() <= 0)
                    {
                      //  holidaysRemaining--;
                        person.HolidaysRemaining--;

                        Holiday holiday1 = new Holiday();
                        holiday1.PersonId = PersonId.Value;
                        holiday1.HolidayDate = startDates;

                        db.Holidays.AddObject(holiday1);
                        db.SaveChanges();
                        //say start date is 10. AddDays(1) will make it 11 then return it to startDates in 'startDates' = startdates,
                        //but doesnt chage the value of startdates = 'startdates'
                    }

            }

            startDates = startDates.AddDays(1);
        }

        return RedirectToAction("Index");
    }

[Bull City Rambler]

//but doesnt chage the value of startdates = 'startdates'

I'm confused about what you mean here. Are you expecting one DateTime value to change because of a change to a different DateTime value? If so, that won't happen because DateTime is a struct, meaning

DateTime foo = day1;
DateTime bar = foo; // bar == day1, foo == day1
foo = day2; // bar == day1, foo == day2

I think I'm missing your question tho.