Hoping you are a true seller and we regret for the bad experience you had as a coseller.
2.DTDC have a courier service something called 'open mode/ open condition' service, wherein you would be paying around 200 to 300 irrespective of the item value.
The process: you will just give them the mobile box with address stapled over the box. No packaging is needed! just a cover wrap to avoid dust and address.
They will note down all the articles/items/parts inside the box and at each courier points in transit, the receiver and forwarder signs on sheets with parts details till it reaches destiny/receiver.
The responsibility lies with them to delivery the item as it is and with all the items till delivered.
1. Lodge a complaint at http://www.indiapost.gov.in/Ccc/PCData.aspx
If you don't get proper resolution, you can escalate issue with concerned (your area) IPS cader officer. You can get mail ids from your local post office.
1a. Alternatively, if you don't want to wait for them, you can put a letter at your post office stating the facts and request to reimburse twice the speed post charges (atleast you will get this amount).
1b. Mainly, you should know if buyer is a true buyer.
1c. You can place an inquire with local India Post to verify the weights at all check points in transit to verify where the problem occurred or everything is fine and buyer is fraud.
1d. You can also lodge a complaint at your police station. If the item is worth and to spend time on retrieving truth.
Hope this helps you and wish you all the best in coming days.
Regards