Hi,
Thank you for the additional information.
Change the code:
if($min_quantity == 0)
$min_quantity = 1;
if($max_quantity == 0)
$max_quantity = (int)$min_quantity * 15;
$values = array();
to:
$values = array();
if($min_quantity == 0)
$min_quantity = 1;
if($max_quantity == 0){
$max_quantity = (int)$min_quantity * 15;
if($max_quantity<$row->cart_product_quantity)
$values[] = JHTML::_('select.option', $row->cart_product_quantity, $row->cart_product_quantity);
}elseif($max_quantity<$row->cart_product_quantity){
$row->cart_product_quantity = $max_quantity;
}
in the file "cart" of the view "checkout" via the menu Display>Views and it should fix the problem.