Need code to call webservice which will transfer CSV data

Read this link. May be it helps you.

 

In this link you have to pass the csv data as json string.

 

https://www.c-sharpcorner.com/blogs/pass-data-using-webapi-in-c-sharp-windows-forms

This article shall describe an approach that may be used to upload any sort of a file through a web service from a Windows Forms application. The approach demonstrated does not rely on the ASP.NET file uploader control and allows the developer the opportunity to upload files programmatically and without user intervention.

 

https://www.c-sharpcorner.com/article/upload-any-type-of-file-through-a-C-Sharp-web-service/