Airtel — Blocked number and not maintaining the details of Customer

Address: Hyderabad

I have ported one of my number to airtel 7 to 8 months ago. Recently they blocked the number saying I have to clear of my old dues form previous service provider. After clearing of the dues my number is not activated. When I call customer care they are telling they dont have any details of the customer with my number. This number is active since its ported and even I have validity during the block period as well.
When they dont even maintain a customer details with a number which is pathetic and also dangerous( What happens if we lost that number and someone misuses).
Need a strict action against this. Airtel has failed to provide a basic service of maintain the details of customer