Ignore Special Characters - Web API C#

PROBLEM: Special characters particularly $ and £ are causing inconsistent behaviour in Web Api - ASP.NET C#. After calling the API the result is sometimes -

RESULT: {"Message":"An error has occurred."}

• REQUEST FORMAT: url + Message;
• FULL API CALL: ".........//api/data?Message=Test%20For%20%245700.00%20at%20"
• MESSAGE: "Test For $5700.00 at "

What I've tried

1. Using Uri.EscapeDataString(request); to call the API, but the result is still not always 100% successful (50% of times it passes, the remaining 50% of times it comes up with the error message above)
2. Removing the $ or £ symbol, it passes every time

QUESTION: Is there a way to allow special characters to pass through the API (just as a string)? Is there any way to get just the plain string back, even when a special character is included? Here's some code below that gets the message -

public List<Results> Get(string Message) { //DO SOMETHING WITH THE MESSAGE AS A STRING & RETURN RESULTS } 

Also, here's how I'm calling the API -

//CALLING API STEPS string url = ".....//api/data?Message="; string message = "Test For $5700.00 at "; string completeURL = url + Uri.EscapeDataString(message); var client = new WebClient(); var content = client.DownloadString(completeURL); 

I've added some additional test results below -

TEST RESULT - PASS

string url = ".....//api/data?Message="; string message = "Test For $5700.00 at "; message = message.Replace("$", "%24");//Adding this line before the URL-encoding fixes the problem string completeURL = url + Uri.EscapeDataString(message); var client = new WebClient(); var content = client.DownloadString(completeURL); //PASS - COMPLETE URL: ".....//api/data?Message=Test%20for%20%25245700.00%20at%20" //RESULT - API CALL SUCCESSFUL 

TEST RESULT - FAIL

string url = ".....//api/data?Message="; string message = "Test For $5700.00 at "; string completeURL = url + Uri.EscapeDataString(message); var client = new WebClient(); var content = client.DownloadString(completeURL); //FAIL - COMPLETE URL: ".....//api/data?Message=Test%20for%20%245700.00%20at%20" //RESULT - EXCEPTION -> "The remote server returned an error: (500) Internal Server Error."