Regex help and string Formatting

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C#

I have this Class as a Javascript Minimizer

using System.IO;
using System.Net;
using System.Text;
using System.Xml;
    /// <summary>
    /// A C# wrapper around the Google Closure Compiler web service.
    /// </summary>
    public class GoogleClosure
    {
        private static string PostData = "js_code={0}&output_format=xml&output_info=compiled_code&compilation_level=SIMPLE_OPTIMIZATIONS";
        //private static string PostData = "js_code={0}&output_format=xml&output_info=compiled_code&compilation_level=ADVANCED_OPTIMIZATIONS";
        private static string ApiEndpoint = "http://closure-compiler.appspot.com/compile";

        /// <summary>
        /// Compresses the specified file using Google's Closure Compiler algorithm.
        /// <remarks>
        /// The file to compress must be smaller than 200 kilobytes.
        /// </remarks>
        /// </summary>
        /// <param name="file">The absolute file path to the javascript file to compress.</param>
        /// <returns>A compressed version of the specified JavaScript file.</returns>
        public static string CompressFile(string file)
        {
            string source = File.ReadAllText(file);
            return Compress(source);
        }
        
        public static string Compress(string source)
        {
            XmlDocument xml = CallApi(source);
            return xml.SelectSingleNode("//compiledCode").InnerText;
        }

        /// <summary>
        /// Calls the API with the source file as post data.
        /// </summary>
        /// <param name="source">The content of the source file.</param>
        /// <returns>The Xml response from the Google API.</returns>
        private static XmlDocument CallApi(string source)
        {
            using (WebClient client = new WebClient())
            {
                client.Headers.Add("content-type", "application/x-www-form-urlencoded");
                string data = string.Format(PostData, UrlEncoder.UrlEncode(source));
                string result = client.UploadString(ApiEndpoint, data);
                XmlDocument doc = new XmlDocument();
                doc.LoadXml(result);
                return doc;
            }
        }
    }

The UrlEncoder Class has UrlEncode(string) and UrlDecode(string) (plus other needed private functions) and it is ripped from HttpUtility in System.Web using Reflector (dont exactly know if i did something illegal but i was pissed from having to switch to normal .net 4 from Client Profile for no reason :mad:).

Then i have the following text in javascript through Google Closure Minimizer...

h="\u0392\u03bb\u03ad\u03c0\u03c9 "+c+"\u03b5\u03b9\u03ba\u03cc\u03bd\u03b5\u03c2",b=true,a;document.getElementById("track2").onclick=d;

What would you suggest as a way for me to reformat this into utf-8 again?
i have tried UrlDecode(text.Replace("\\u0","%u0"));
but it leaves the "+" symbols blank.

What i want is to replace the \u0392(6 chars) with the corresponding utf8 char (and not only (\u0392) obviously).