Issue on wcf service while transfer file.

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C#

WCFServices

i have implemented wcf service which is for transfer a file into E drive on client system.it is working for the first time is good.when i call the service from second time it showing error message like "file is already existed".
now i want to implement the service if the file is already existed in E drive i want to change the file name by adding 1 number at last to the file.
for example file name is ram.docx.
if the file existed in E drive just i want to change file name into ram1.docx
if ram1.docx file existed in E drive just i want to change file name into ram2.docx
this is what exactly i want to do.

My code is :

code for wcf interface:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.Text;

namespace DemoonWCFservice
{
    // NOTE: You can use the "Rename" command on the "Refactor" menu to change the interface name "IHelloservice" in both code and config file together.
    [ServiceContract]
    public interface IFiletransfer
    {
       
        [OperationContract]
        void Getfile();

    }
}

i have implemented this method in Filetransfer class

code for Filetransfer:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.Text;
using System.Web;
using System.IO;

namespace DemoonWCFservice
{
    // NOTE: You can use the "Rename" command on the "Refactor" menu to change the class name "Helloservice" in both code and config file together.
    public class Filetransfer : IFiletransfer
    {
        


        public void Getfile()
        {

            string source=@"D:\Swathi\DemoonWCFservice\DemoonWCFservice\Info\RAMPRADEEP KALIVARAPU (1).docx";
            string destination=@"E:\RAMPRADEEP KALIVARAPU (1).docx";
            File.Copy(source, destination);


        }
    }
}

please provide me a solution for this.