foreach my $sub1 ( sort keys %{ $doc } ){

  ... # $sub1

    foreach my $sub2Hash ( @{ $doc->{$sub1} } ){

        for my $sub2 ( sort keys %$sub2Hash ){

            unless (ref($sub2Hash{$sub2})) {

                ...  # $sub2
                $worksheet->Cells($rowCount, $colCount)->{Value} = $sub2;
                $worksheet->Cells($rowCount, $colCount)->{Value} = $sub2Hash{$sub2};
                next;

            }

            foreach my $sub3Hash( @{$sub2Hash{$sub2}} ){

                for my $sub3 ( sort keys %$sub3Hash ){