Webrequest to web api (oh god why)

WebRequest.cs

        public static string PostImage(byte[] imageBytes)
        {
            string output;

            var boundary = GetBoundary(); //boundaries are placed between every form value and file in a MIME message
            var boundaryFormatted = string.Format("--{0}\r\n\r\n", boundary);
            var boundaryBytes = Encoding.ASCII.GetBytes(boundaryFormatted); //this is ascii, but later on everything is encoded in UTF8. Why, you ask? I do not know.


            var partFormat = "--{0}\r\nContent-Disposition: form-data; name=\"{1}\"\r\n\r\n{2}\r\n"; //this format is for form data values, which we are not using
            var fileHeaderFormat = "--{0}\r\nContent-Disposition: form-data; name=\"{1}\"; filename=\"{2}\"\r\n"; //this format is specifically for files

            var request = (HttpWebRequest)WebRequest.Create(EndPointUrl);
            request.KeepAlive = false;
            request.Method = "POST";
            request.ContentType = string.Format("multipart/form-data; boundary={0}", boundary); //MIME content type header

            using (var memoryStream = new MemoryStream())
            {
                var fileHeader = string.Format(fileHeaderFormat, boundary, "fieldNameHere", "audio-card-3.jpg"); //header formatting
                var headerBytes = Encoding.UTF8.GetBytes(fileHeader); //everything in bytes w/ memstream
                memoryStream.Write(headerBytes, 0, headerBytes.Length); //write dat
                var contentType = "Content-Type: image/jpeg\r\n\r\n"; //jpg content type. at this point we are beginning to encode the image
                var contentBytes = Encoding.UTF8.GetBytes(contentType);
                memoryStream.Write(contentBytes, 0, contentBytes.Length); //write dat contenttype


                memoryStream.Write(imageBytes, 0, imageBytes.Length); //THIS LINE WRITES THE IMAGE BUFFER.

                memoryStream.Write(boundaryBytes, 0, boundaryBytes.Length); //write dat boundry

                var lastBoundary = string.Format("--{0}--", boundary); //last boundary ends the mime message and compliant consumers will blow up without it
                var lastBoundaryBytes = Encoding.ASCII.GetBytes(lastBoundary);
                memoryStream.Write(lastBoundaryBytes, 0, lastBoundaryBytes.Length); //write dat

                request.ContentLength = memoryStream.Length;

                using (var requestStream = request.GetRequestStream())
                {
                    memoryStream.Position = 0; //take the memstream
                    var memBuffer = new byte[memoryStream.Length];
                    memoryStream.Read(memBuffer, 0, memBuffer.Length); //read it into membuffer
                    memoryStream.Close();
                    requestStream.Write(memBuffer, 0, memBuffer.Length); //write membuffer to request stream
                }
            }

            using (var response = request.GetResponse()) //send the MIME message
            {
                using (var responseStream = response.GetResponseStream())
                {
                    using (var reader = new StreamReader(responseStream))
                    {
                        output = reader.ReadToEnd();
                    }
                }
            }

            return output;
        }