Different menu on different pages

Good Evening,

My client wishes to separate their site into two different sections. I have created two menu’s which link to different pages.

As an example, one menu is called cars, one menu is called motorcycles. Each of these menu’s have their own links:

/cars/our-cars
/cars/our-cars/hatchbacks

/motorcycles/our-motorcycles
/motorcycles/our-motorcycles/honda

Following advice from other threads on this forum, I have also created a child theme, and also copied over /includes/helper-main-menu.php.

I have copied in code below that I have added to /includes/helper-main-main.php within my child theme for the purposes of identifying the page ID, and outputting the relevant menu. I replaced 'menu_id' =>$avia_menu_class with 'menu_id' => '12', however this does not retrieve either of the menu’s. Any help or advice would be greatly appreciated.

<div class='container'>
			      <?php
			            /*
			            *	display the themes social media icons, defined in the wordpress backend
			            *   the avia_social_media_icons function is located in includes/helper-social-media-php
			            */
						$nav = "";
						
						//display icons
			            if(strpos( $headerS['header_social'], 'extra_header_active') !== false) echo $icons;
			            if ( is_page( array(336, 208, 51, 376, 129) ) )
							{
							    echo "Cars Menu Required";
							    /*
						*	display the main navigation menu
						*   modify the output in your wordpress admin backend at appearance->menus
						*/
						    // $extraOpen = $extraClose = $icon_beside = "";
						    // if($headerS['header_social'] == 'icon_active_main' && empty($headerS['bottom_menu'])){$icon_beside = " av_menu_icon_beside"; }
						    // if($headerS['bottom_menu']){ $extraClose = "</div></div><div id='header_main_alternate' class='container_wrap'><div class='container'>";  }
						
						    // echo $extraClose;
						
						    // echo "<nav class='main_menu' data-selectname='".__('Select a page','avia_framework')."' ".avia_markup_helper(array('context' => 'nav', 'echo' => false)).">";
						    //     $avia_theme_location = 'avia';
						    //     $avia_menu_class = $avia_theme_location . '-menu';
						    //     $args = array(
						    //         'theme_location'	=> $avia_theme_location,
						    //         'menu_id' 			=> '12',
						    //         'menu_class'		=> 'menu av-main-nav',
						    //         'container_class'	=> $avia_menu_class.' av-main-nav-wrap'.$icon_beside,
						    //         'fallback_cb' 		=> 'avia_fallback_menu',
						    //         'walker' 			=> new avia_responsive_mega_menu()
						    //     );
						
						    //     wp_nav_menu($args);
						
							}
							elseif ( is_page( array(338, 372, 374, 376, 380) ) )
							{
								echo "Motorcycles Menu Required";
						/*
						*	display the main navigation menu
						*   modify the output in your wordpress admin backend at appearance->menus
						*/
						    $extraOpen = $extraClose = $icon_beside = "";
						    if($headerS['header_social'] == 'icon_active_main' && empty($headerS['bottom_menu'])){$icon_beside = " av_menu_icon_beside"; }
						    if($headerS['bottom_menu']){ $extraClose = "</div></div><div id='header_main_alternate' class='container_wrap'><div class='container'>";  }
						
						    echo $extraClose;
						
						    echo "<nav class='main_menu' data-selectname='".__('Select a page','avia_framework')."' ".avia_markup_helper(array('context' => 'nav', 'echo' => false)).">";
						        $avia_theme_location = 'avia';
						        $avia_menu_class = $avia_theme_location . '-menu';
						        $args = array(
						            'theme_location'	=> $avia_theme_location,
						            'menu_id' 			=> $avia_menu_class,h
						            'menu_class'		=> 'menu av-main-nav',
						            'container_class'	=> $avia_menu_class.' av-main-nav-wrap'.$icon_beside,
						            'fallback_cb' 		=> 'avia_fallback_menu',
						            'walker' 			=> new avia_responsive_mega_menu()
						        );
						
						        wp_nav_menu($args);
							}
							else 
							{
								echo "Whoops, no menu assigned!";
							}
						//display navigation
						if(strpos( $headerS['header_secondary_menu'], 'extra_header_active') !== false )
						{
			            	//display the small submenu
							//CSM commented out
			            	/*
			                $avia_theme_location = 'avia2';
			                $avia_menu_class = $avia_theme_location . '-menu';
			                $args = array(
			                    'theme_location'=>$avia_theme_location,
			                    'menu_id' =>$avia_menu_class,
			                    'container_class' =>$avia_menu_class,
			                    'fallback_cb' => '',
			                    'container'=>'',
			                    'echo' =>false
			                );
			                
			                $nav = wp_nav_menu($args);
			                */
						}