>I thought of that Viv I think it involves using the Microsoft Ace OLEDB driver if reading .xlsx files which mine will be

Maybe this : http://www.codeproject.com/Tips/801032/Csharp-How-To-Read-xlsx-Excel-File-With-Lines-of
Haven't tried it.

Assuming the spreadsheet has a known format you could then build up an array of objects for each row and then use the serializer I mentioned earlier to produce the scv file...

Haven't you changed your clock yet :-}