VBA script- save file with current filename

Hi guys, I'm sure this is an easy one but I couldn't find anything from searching.

I want to save the current .csv file and a .txt with the same name. The file type is not problem but I can't find out how to specify the filename as the current filename.

Thanks in advance for any help,
James


EDIT
This is what I have now but I want "Filename.txt" to be the current workbook filename.

ActiveWorkbook.SaveAs Filename:= _
"C:\Users\user\Documents\Emails\5Milla\Full Email File_1.csv_Pieces\Filename.txt" _
, FileFormat:=xlText, CreateBackup:=False