string fileAndPath = @"c:\webserver\public\myCompany\configs\promo.xml";
string currentDirectory = Path.GetDirectoryName(fileAndPath);
string fullPathOnly = Path.GetFullPath(currentDirectory);
var fn = openFileDialogSapTable.FileName;
var currentPath = Path.GetFullPath( fn );
currentPath = Directory.GetParent(currentPath).FullName;