Delhivery Private Limited - Personal package worth is missing as per the customer support

Have shipped my unsealed package from my hyderabad (on **nd July ****) to Bangalore. Package has reached the last dispatch center within * days as per the tracking. After that no update at all. Customer care support says that they lost the package and they are searching still. It’s been more than a ** days they are searching my package. Whenever I contact them they say that their team is searching and that’s it. Since * days they even stopped to respond my email. I am going to sue them for the loss and their irresponsible behavior.