Make validation on the phone number not to recieve agift when clicking checkbox

Please i need help.
I have created a checkbox in the checkout page, so that when clients clicked on the checkbox he will receive a gift so far everything goes well.
Now i have decided to make validation on this checkbox, this validation occurs using the phone number of the client, which means if the client of a specific phone number (this is known through the comparison of the phone number inserted and that saved in the database) have received a gift (which is saved in the database where billing checkbox created is equal to 1) the client will not receive another gift.
I have written a code and add an error in order to know if everything seems right but it is not working

add_action( 'woocommerce_checkout_process', 'wc_remove_checkout_fields11' );
function wc_remove_checkout_fields11($current_user_id){
        $current_user_id = get_current_user_id();
        $phone = get_user_meta($current_user_id ,'_billing_phone',true);
	    $billing1= get_user_meta($current_user_id ,'billing_checkbox',true); 
	    $phone2=$_POST['_billing_phone'];
	
  if ( isset( $_POST['billing_checkbox'])  ) {
	  
		if($phone==$phone2 && $billing1==1){
			remove_action( 'woocommerce_after_checkout_validation', 'place_test_request211',10 );
			   wc_add_notice( 'we already have a user with the same mobile number and has recieved the gift', 'error' );
			
		}
	elseif($phone==$phone2 && $billing1==0){
		wc_add_notice('phone equal but not recieved a gift','error');
		add_action(  'woocommerce_after_checkout_validation', 'place_test_request211',10,1 );
	}
	elseif($phone!=$phone2 && $billing1==1){
		wc_add_notice('phone not equal but recieved a gift','error');
	 add_action(  'woocommerce_after_checkout_validation', 'place_test_request211',10,1 );
	}
	  elseif($phone!=$phone2 && $billing1==0){
		 add_action(  'woocommerce_after_checkout_validation', 'place_test_request211',10,1 );  
	  }
	 }
}

This is my code where i have added action inside the if clause in order not to stop the action of adding a gift, and remove action to stop the action of adding a gift. but it is not working. any advise and help please