Well... In a nutshell - mission accomplished!
Pretty much solved with a combination of tips from above so thanks all.
Firstly, I added the "PAUSE" line to the file. This helped because it kept the DOS box on the screen which allowed me to see "The Command Syntax Is Incorrect" (or similar) after each step. I fiddled around a little by adding the full path to the renamed file but it didn't seem to help at all.
I then tried what ultimately seems to be a combination of what Shuttlebus and Seacue proposed. By pointing the cursor to the appropriate directory with a cd c: \folder 1 command line followed by a rename *.xls *.csv, this seemed to work.
Saab - I know what you mean about where the batch file is actually located. My 2 files were in separate directories to where all the Excel files were. However I kept the EXIT line in the file and it all worked still - didn't really seem to make any difference. Maybe because I put PAUSE ahead of it, it never really got to the EXIT step???
Anyway - thanks to the communal brainpower here. Combining a number of tips achieved the desired result so once again, big thanks to all!