I believe you can allow .NET to do its thing and just use Javascript and the browser to decode the characters (or everything) if that is what you need. The following stack question addresses how to do this with just javascript: Decode & back to & in JavaScript. Based on that you would probably be looking at something like:
var div = document.createElement('div');
div.innerHTML = encoded;
var decoded = div.firstChild.nodeValue;
Hope that helps!