Unable to add a product to cart from a module

[prak]

Hello, I have a product with an attribute called "Cloth" with two values. I am trying to create a module named "customizeproducts" for the product page which would allow the user to choose the value and add the product to cart. ( I know that prestashop allows it by default but I want to accomplish it with my module ) I have added a button to add the product to cart using cart->updateQty(). However, I am getting this error "Product not found product no longer available" on clicking the button. Refreshing the page after sometime shows that the cart is not empty.

Here is my code:

 

customizeproducts.php

  public function hookDisplayFooterProduct()
    {
      $product_id = $_GET['id_product'];
      $product = new Product($product_id);
      $int_product_id = (int)$product_id;
      $currency = "rupees ";
      $newcart = new  Cart($this->context->cookie->id_cart);
      $product_price =  ($currency).$product -> price;
      $product_name = $product -> name[1];
      $attrs=$product->getAttributesGroups($this->context->language->id);
      $quantity = 1;
      $id_customization = (int)Tools::getValue('id_customization');
      $operator = Tools::getValue('op','up');
      $id_address_delivery = (int)Tools::getValue('id_address_delivery');
      $this->context->smarty->assign(
    array(
        'customize_products_name' => Configuration::get('CUSTOMIZEPRODUCTS_NAME'),
        'customize_products_link' => $this->context->link->getModuleLink('customizeproducts', 'display'),
        'name'    => $product_name,
        'id'      => $int_product_id,
        'price'   => $product_price,
        'attrs'   => $attrs,
        'cart' => $newcart,
        'quantity' => $quantity,
        'id_customization' =>$id_customization,
        'operator' => $operator,
        'iad' => $id_address_delivery
    )
    );
    return $this->display(__FILE__, 'customizeproducts.tpl');
    }

customizeproducts.tpl

  {foreach from=$attrs key=id_attribute_group item=group}        
        <a class="exclusive button ajax_add_to_cart_button"
         href="{$cart->updateQty($quantity,$id,$group.id_attribute,$id_customization,$operator,$iad)}">
          <span>{$group.attribute_name}</span>
        </a>
    {/foreach}

How can I solve this issue?