Yes you can tender the "deficiency in service caused to you" in form of a letter. Legal Notice is as such not defined anywhere in law but should be having included threat to grab the legal implications.
You can send a notice letter but not a 'legal notice'. The legal notice is a different concept and needs legal drafting skill available to lawyers. The others authorised to notify legally are NGOs working in the concerned field to assist people in pursuing legal matters and are also authorised to represent under the provisions of concerned acts.
An A/D Regd. Post letter is the Cheapest & best way to do it.
Postal department has abruptly stopped 'UCP' (Under Certificate of Posting). This is v.v. unfair. This needs to be revived. Maybe Postal agency can charge Rs 5/- and make it a bit more fool proof with a computer based number etc attached with every article. But, this service should be revived. Members should take up/help this cause.
Send it just as a regular notice like a landlord gives a notice to his tenant. In practice legal notice is sent by an advocate under the instructions from his client so that the notice-receiver takes it seriously.