excel to json converter

We are searching for a programmer, who can write us a customized json converter. we have a excel file with some data columns (not more than 200 row and 20 columns) we want these data converted to json files. The problem is, that the json files are nested differently to the csv files und it has different names accordingly. These nestings and file names should be matched through the script. Programming language and approach is open to discuss. It can be a stand alone command line converter or a vba script. Just make suggestions. We are developing a mobile learning game and that is the way we import data to it. We are working with Unity and C#, so it would be much appreciated, if it was in C#, so we can easily customize the script later for our needs We like to pay a fixed price for that. Source Code should be included. We deliver the Excel file and an example json file together with some explanations. Just contact us for further instructions.