The Professional Couriers — failure to deliver my letter

Address:

Shimoga, Karnataka, 577204

Date of sending courier 21/08/2017
Service provider: professional couriers ground floor, rkt complex, durgigudi, shimoga.
Description :
On 21/08/17 i sent a courier to venkatesh gore, mala, mullur, karkala, udupi dist. No smg3852477 (From shimoga office durgigudi) the courier consisted invitation to my housewarming ceremony. The courier service did not deliver my letter stating that the phone number that i have mentioned in the address was not correct. When i went to the courier office to enquire about the delivery status, they harshly replied me that the phone number on the envelope was not reachable hence the letter could not be delivered, however, they did not return my courier either.
I have been using professional couriers from the last ten years and was very happy with the committed service provided but after this incident, i have lost hope on the company and i have started to doubt the credibility of the nature of their working style.
My first complaint is that the delivery system (According to my observation) completely depends on the phone number on the cover and if the number is not reachable or incorrect they never care to check the address or to deliver it on the basis of the address written on the envelope. Let me remind you that professional couriers should not work on the basis of phone number but on the basis of the address written, its cargo and courier service, not sms or mobile service.
My second complaint is that they never cared to return my letter.

After the incident, some of my relatives did not attend the housewarming ceremony stating that they did not receive invitation.
Desirable resolution of my complaint:
I want my letter back, an apology letter for not doing the work properly and a full refund of 60 rupees (Alas! India post would have delivered my letter for 4 rupee stamp, what a fool i am to rely on professional couriers!!!)