Stop excel prompt asking if you want to save changes

I have been writing an application that needs to save a document in .csv format. I have managed to get the application to work but it prompts me to save changes (please see the attached file).

The code that I am using in shown in the snippet below but I would be grateful if someone could provide information on how to stop getting this prompt and select yes.

I dont know if there is also any documentation available on objects that you create within vb.net (e.g Dim oExcel As Object = CreateObject("Excel.Application")) to describe the various methods and parameters that are available to the programmer.
With this being a user defined object I dont get the information from within vb.net.

Thanks
 

oBook.SaveAs("C:\tempOpenItems.csv", Excel.XlFileFormat.xlCSVWindows)

Select allOpen in new window

PopUp.doc