Need help with renaming formatting

I'm trying to figure how to format rename the songs to only keep '[A]' for m4a files '[C]' for Mp3CBR and '[V]' for Mp3VBR files. if anyone can help

here's my current script
$left(E:\3%genre%%albumartist%$if(%composer%,$upper('['%composer%']'),)$upper('['$left($right(%_extension%%_vbr%,2),1)']')'['%_total%%totaltracks%']' %album%%discnumber%.$num(%track%,2) %title%,240)

For that part that inserts the

You could try
(I haven't got an m4a file at hand - you would need to check which string as search string would be correct)