After checking i mark that I am passing
<form runat="server" method="post" action="http://localhost:37542/AccountService.svc/UploadReceipt">
Which should be
<form runat="server" method="post" action="http://localhost:37542/AccountService.svc/UploadReceipt?CompanyCode=1&FileName=Test&FileContent=/9j/4AAQ">
Any ways thanks for your support :)