How to get the request sending from a web service to another locally?

If just to get the request from my website directly to a third party api, it's fairly simple using fiddler.

I do have web service created directly talk to the third party api which is working fine, if i use the dll of the web service project to talk to my website.

However, after i hosted the web service project remotely, then i'm having a trouble to get response from the third party api, and it complaining the send body has invalid characters included or missing data element.

Therefore, I was trying to compare the request send through. I can get the request locally really easy, but how can i get the request from remote server without get into the server.

Someone please help, much much appreciated!