use strict; 
use warnings;

my $print_flag = 'N';

while (<DATA>) {
    if ($print_flag eq 'Y') {
        print;
        $print_flag = 'N';
    }
    $print_flag = 'Y' if m/^Customer ID: Yes/;
}

__DATA__
Customer ID: none
VT : 002/89

Customer ID: Yes
VT: 001/89

Customer ID: none
VT: 006/85

Customer ID: Yes
VT: 003/56