在CodeIgniter中更新数据

I'm working on a project on CodeIgniter, but I got an issue right now, I tried to resolve it, but this got the problem.

Here we are : In my code below, I can't update whatever I wan't on my database, but I can insert whatever in.

I'm supposed to update 'mode' from 'landing news soir' to 'landing Offre Gratuite' on the row depending on customer_id.

EDIT : Yeah sry I should've precised that I tried something like if(1===1) but still can't update data.

    elseif($all === "gratuite") 
        {    
            $mode1="landing news soir";
            $mode2="landing Offre Gratuite";

            $this->db->select('mode');
            $this->db->where('customer', $customer_id);
            $this->db->where('mode', $mode1);
            $query= $this->db->get('newsletters_inscriptions');


            $update_data = array(
                    'mode' => $mode2);

            if($query->row()){

                $this->db->where('customer', $customer_id);
                $this->db->update('newsletters_inscriptions', $update_data);
            }

            else{

                $insert_data = array(
                'newsletter' => '2',
                'customer' => $customer_id,
                'liste' => 175,
                'mode' => 'landing Offre Gratuite');

                $this->db->insert('newsletters_inscriptions', $insert_data);
                $newsletter_inscription_id = $this->db->insert_id();

                // Mise en base dans la liste des objectifs - Stats logs tracking
                $this->stats->enregistrer_objectif(null, $this->inscription_newsletter, $customer_id, $newsletter_inscription_id);
            }
        }

I tried a lot o' ways to resolve it but still can't make it. Thank you.