First off, s/^\s+|\s+$//g; isn't doing what you think it's doing, but that's not your problem.

Your problem is that you're making it too difficult for yourself. Either

• the line begins with BNA, in which case you have a new entry
• the line doesn't being with BNA, in which case you push it onto the fields array of the last entry you saw.

my @stuff;

while (<DATA>)
{
    my @fields = split $Delimiter, $_;

    my ($type, $name) = $fields[0] =~ /^(...)(.*)/;

    if ($type eq 'BNA')
    {
        # I don't know what other data you want to keep from the BNA l
+ine ...
        push @stuff, {
            name => $name,
            products => [],
        };

        next;
    }

    # I don't know what you want to do with this, so I'll just keep it
+ there.
    push @{$stuff[-1]{products}}, $_;
}
[download]

Code is untested, but should work just fine.