C# class for reading,writing and converting invoices and creditnotes between OIOUBL and PepPol

I'm looking for a C# class that will allow me to read, write and convert invoices and creditnotes between OIOUBL and PepPol formats. It is important that the class allows for the conversion of both formats, as this will be vital to the functionality of the system. I'm willing to be flexible with deadlines, however would like this project to be completed at a reasonable pace. It is also imperative that the class includes specific features or functionalities that meet my needs. The class shoud have functionality to validate the documents in a reasonable way (required optional fields) We want an Excel document describing the mapping of fields and information about fields missing for a valid conversion between the formats (handling of optionel and required fields) It should also be possible to create the documents within code with the class - r/w fields for content [login to view URL] [login to view URL] If you believe you are capable of creating the C# class I am seeking, please contact me and we can discuss the project further.