using System;

using System.Web;

public class Program

{

    public static void Main()

    {

        var AttempIDQA = "982607974%3a%3a121187813%3a%3a50236c36b2d22ab2222d8f94f362f2ba";

        var AttempIDPROD = "1%257c188415434%257c6f5f2570-a87a-4371-ad06-43ddb66e0b1d_Y8ILJ%257cfUZTuL0wdYhJFE%252fpE7Trtg%253d%253d";

        while(AttempIDPROD.IndexOf('%')>0){

            AttempIDPROD = System.Web.HttpUtility.UrlDecode(AttempIDPROD);

        }

        while(AttempIDQA.IndexOf('%')>0){

            AttempIDQA = System.Web.HttpUtility.UrlDecode(AttempIDQA);

        }

        Console.WriteLine(AttempIDPROD);

        Console.WriteLine(AttempIDQA);

​

    }

}