previous row value to be fetched

Here i want to get previous row balance value in to my field.the last id of customer_id '16' of balance is 200 but i want to get the previous ids value in to the field and this is my table

    id  order_id    customer_id  amount     actual_amount   paid_amount     balance     type
    25  11            16                        100.00        50.00         50.00       Cash
    26  12            16                        200.00        100.00        100.00      Cash
    27  13            16                        150.00        100.00        50.00       Cash
    28  14            16                        300.00        250.00        50.00       Cash
    29  14            16                        170.00        100.00        70.00       Cash
    30  15            16         100            170.00        70.00         100.00      Cash
    31  16            16         400            500.00        300.00        200.00      Cash

this is my model

public function order_balance($order_code)
{
    $this->db->join('services','payment.customer_id=services.customer_id','left');
    $this->db->select('payment.*,payment.balance,payment.actual_amount,payment.customer_id');
    $this->db->order_by('payment.id','desc');
    $query = $this->db->get_where('payment',array('code' => $order_code));
    return $query->previous_row();
}

this is my control

 public function final_payment($order_code)
{
    $data['active_mn']='';
    $data['result'] = $this->Account_model->order_balance($order_code); 
    $this->load->view('final_payment',$data);
}

my services table looks like this..

    id  code      customer_id   particulars     
    11  ORD00011    16              phone   
    12  ORD00012    16              gdf     
    13  ORD00013    16              ghgfh   
    14  ORD00014    16               tv     
    15  ORD00015    16              ghfg    
    16  ORD00016    16               tv     
    17  ORD00017    16              gdfg    
    18  ORD00018    16              desk    
    19  ORD00019    16              gdf     

my result should be like this

 id      order_id    customer_id     amount    actual_amount   paid_amount  balance     type
 31        16            16           400         500.00         300.00     100.00      Cash