How to prevent "&" from being converted in "&" when doing xml serialization in ASP.NET Web API?

I am creating a booking service using ASP.NET Web API,

For which response model it looks like this:

[XmlRoot("RateList")]
public class RateList
{
    [XmlElement("Rate")]
    public List<Rate> Rate { get; set; }

}
public class Rate
{
    [XmlAttribute("Code")]
    public string Code { get; set; }
    [XmlAttribute("ErrorMessage")]
    public string ErrorMessage { get; set; }
     [XmlElement("RoomRate")]
    public List<RoomRate> RoomRate { get; set; }
}
public class RoomRate
{
    [XmlAttribute("URL")]
    public string URL { get; set; }
}

The response must be in XML format, so I have serialized from below,

return Request.CreateResponse<RateList>(HttpStatusCode.OK, objRateList, Configuration.Formatters.XmlFormatter);

my Global.asax file

WebApiConfig.Register(GlobalConfiguration.Configuration);
        var xml = GlobalConfiguration.Configuration.Formatters.XmlFormatter;
        xml.UseXmlSerializer = true;

The actual response must be like this:

<RateList 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <Rate Code="174511">
        <RoomRate URL="https://somedomain.com/planning/booking?start=2015-06-02&end=2015-06-04&id=174511&adults=2&childAges=0&room=1"/>
</Rate>
</RateList>

But currently, I get a response like the following, where the "&" is changed to " &":

<RateList 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <Rate Code="174511">
        <RoomRate URL="https://somedoamin.com/planning/booking?start=2015-06-02&amp;end=2015-06-04&amp;id=174511&amp;adults=2&amp;childAges=0&amp;room=1"/>
</Rate>
</RateList>

How can I avoid this change in my reply?

Thanks in advance.