You have an unfortunate field delimiter, so something like this might help:

while(<DATA>) {
    my $str = $_;
    $str =~ s/!,!/!:::!/g;
    my @parts = split(':::', $str);
    print join("==>", @parts), "\n";
}
[download]

Output:

!A001ST!==>!98!==>!1!==>!01/10/1999!==>!EUROPEENNE!==>!0!==>!EUR!==>!6
+!==>!7!==>!0!==>!98!==>!1!

!A001ST!==>!AD,CD!==>!1!==>!20/05/2004!==>!ANDORRA!==>!0!==>!EUR,USD!=
+=>!6!==>!7!==>!0!==>!AD!==>!1!
[download]