A summary field with the "total of" option might compute the total of the above calculation. That will give you the count of all records in the current found set where the call back is overdue. There are also ways you might use with a relationship or ExecuteSQL to produce the same type of aggregate value.
And you might use the TimeStamp function to take a date and time field as parameters to return the equivalent time stamp as a slightly simpler way to combine the date and time into such a value instead of getastimestamp.
I think the ExecuteSQL will work best if I could figure out how to check if date field is earlier than today and time field is earlier than current time?
Any suggestions on how to do this in SQL?
You may need to define a calculation field that combines date and time into a timestamp.
WHERE table.TimeStampField < ?
and use Get ( CurrentTimeStamp ) as the optional parameter