fix input with bind params and mysqli_insert_id

<?php
include'konpros.php';

$nminstansi = $_POST['nama_instansi'];
$alamatinstansi = $_POST['alamat_instansi'];
$emailinstansi = $_POST['email_instansi'];
$nmpemohon = $_POST['nama_pemohon'];
$alamatpemohon = $_POST['alamat_pemohon'];
$nmrpemohon = $_POST['nomor_telepon_pemohon'];
$emailpemohon = $_POST['email_pemohon'];

$stmt_konsumen = mysqli_prepare($koneksi, "INSERT INTO tabel_konsumen(nama_instansi, alamat_instansi, email_instansi, nama_pemohon, alamat_pemohon, no_telp, email_pemohon) VALUES (?, ?, ?, ?, ?, ?, ?)");
mysqli_stmt_bind_param($stmt_konsumen, 'sssssss', $nminstansi, $alamatinstansi, $emailinstansi, $nmpemohon, $alamatpemohon, $nmrpemohon, $emailpemohon);
$result_konsumen = mysqli_stmt_execute($stmt_konsumen);

if ( $result_konsumen ) {
  $id_konsumen = mysqli_insert_id($koneksi);
  $tanggal = date("Y-m-d H:i:s");
  $tglsurat = $_POST['tgl_surat'];
  $nosurat = $_POST['nosurat'];
  $dataminta = $_POST['jenis_data'];
  $jumlahunit = $_POST['jumlah_unit'];
  $jumlahwaktu = $_POST['jumlah_waktu'];
  $jenistarif = $_POST['jenistarif'];
  $total = $_POST['total'];
  $lsa = $_POST['lsa'];
  $proposal = $_POST['proposal'];
  $surat = $_POST['surat'];

  $stmt_transaksi = mysqli_prepare($koneksi, "INSERT INTO tabel_transaksi (tgl_input, tgl_surat, no_surat, jenis_data, jumlah_unit, jumlah_waktu, jenis_tarif, harga_total, nama_lsa, proposal, surat, id_konsumen) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)");
  mysqli_stmt_bind_param($stmt_transaksi, 'sssssssssssi', $tanggal, $tglsurat, $nosurat, $dataminta, $jumlahunit, $jumlahwaktu, $jenistarif, $total, $lsa, $proposal, $surat, $id_konsumen);
  $result_transaksi = mysqli_stmt_execute($stmt_transaksi);

  if ( $result_transaksi ) {
    echo "<script>alert('DATA BERHASIL DI INPUT'); window.location = 'forminput.php'</script>";
  }
  else {
    echo "gak masuk transaksi <br />";
  }
}
else {
  echo "gak masuk konsumen <br />";
}