How to change the text of availability of product

-- url of the page with the problem -- : kosmima-gkiotli.gr
-- HikaShop version -- : 2.6.3
-- Joomla version -- : 3.5.1
-- PHP version -- : 5.4.45
-- Browser(s) name and version -- : Firefox 46.0.1

Hi,
I was able to display the text "Available in 3 to 5 days" when I put nothing in the field quantity (on product), as I have change the code in file “quantity” as I have found the line : if($this->row->product_quantity == -1) {“
and I have put the code :
$text = JText::_('Παράδοση σε 3 με 5 μέρες');
echo '<span class="hikashop_product_stock_count">'.$text.'<br/></span>';

But I don't know how to make a code which will display the text "Available in 1 to 15 days" when the value in field "quantity" of the product is "-2"
Could you help me;

Thanks in Advances

I try it, but the page is like the photo that I have attached and named "with changed code", you can see the photo named "with normal code" to see the difference. Also I have attached the "normal quantity.php.txt" and the "changed quantity.php.txt" to see the differece, I believe that it will help.

Hi,
I have turn on the "error reporting" and when I change the code as you said to me display the follow message:

"Parse error: syntax error, unexpected '}' in /var/www/vhosts/kosmima-gkiotli.gr/httpdocs/templates/protostar/html/com_hikashop/product/quantity.php on line 186"

Could you take a look?
If you want I could send you the username and the password of the site.

Hi,
I have attached the full file content .

Hi,
Ok now it works correct with the above code:

if($this->row->product_quantity == -1) {
$text = JText::_('Διαθέσιμο σε 1 έως 5 μέρες');
echo '<span class="hikashop_product_stock_count">'.$text.'<br/></span>';
}
if($this->row->product_quantity == -2) {
$text = JText::_('Διαθέσιμο σε 1 έως 15 μέρες');
echo '<span class="hikashop_product_stock_count">'.$text.'<br/></span>';
}

if(($this->row->product_quantity == -1 || $this->row->product_quantity == -2)) {

Thanks for your support

Hi,
I have made the changes and appears perfect but when a customer try to complete a order with a product that has "quantity == -2" the system doesn't complete the order, because the system thinks that the product it is not available. Can I disable that property or via code or via option of the system. So to can the customer to complete the order without problem?

Thanks in advances

Hi,
as you can see on the image that I have attached the folder "classes" does't exist on "administrator/components/com_hikashop", I have found the file "cart.php" on folder "controllers" but there aren't the line
"if($product->product_quantity!=-1 && $product->product_quantity < $product->cart_product_quantity){"
what is wrong?

It works! thank you!