Batch file conversion program

I need a program written in C# that will perform file conversions to and from xml files to and from fixed length flat file formats. The program requirements are: 1. the program will convert three different file formats. Two from xml to flat file format, and one from flat file format to xml. 2. The files to be converted contain confidential information and will be provided upon placing of the bid and acceptance of the NDA agreement. However, I can tell you that we are converting to/From standard SAP document types (IDOC). 3. we must be able to pass in at the command line what file is to be processed, as well as what the file type is. Code must be well commented and able to be understood by a standard programmer.