Save File

I am having trouble saving a file in a different location but using the same file name.
I open the file from the "C:\Aus_Nav\2011\August" folder and then I change the data automatically through some other code and then after that code is run I want to save it by default back one folder "C:\Aus_Nav\2011\" folder. I want it this way as next year the opening folder would be "C:\Aus_Nav\2012\August" and I would want it to be saved into "C:\Aus_Nav\2011\". Even better would be to save it into the a folder that is the current month the file is being saved (I don't think this 2nd option is possible and that's why I suggest the other option).

The "Application.Dialogs(xlDialogSaveAs).Show" uses the same file name as I want but it saves it into the same folder it was opened from. I've research for many hours and tried several ways but have succeeded.

I would appreciate any help anyone can give me.