Postal stamps — Complaint againt the rude behaviour

I want to file a complaint against the employees at the Padmanabha Nagar Post office, for their rude behaviour. I wanted to purchace stamps for local posting and enquired if I can get 1Re stamps to which the person at the desk said that it is no more available & that the minimum amount stamps available is only 5rs and above. He did not mention that they even have 4rs stamps available for open-posts. Hence as i didnt not have anyother option given by the postal employee I purchaces 5rs ten stamps at 1:30pm in the afternoon. After gettting to know that the post office also sells 4rs stamps, i returned back to the post office at 2:30pm immediately after their lunch time, to exchange the 5rs stamps for the 4rs stamps. However they only abused me & rudely disagreed to take back the 5rs stamps and told that "GOODS ONCE SOLD CANNOT BE TAKEN BACK", like they had sold some electronic or some costly articles. I also told them that I needed those 4rs stamps urgently as I had to post some obituary cards to my relatives, and that I did not have extra money to buy 4rs stamps. Even after several pleading and begging them they turned a deaf ear on me and only kept abusing me.

Please have some one look in to this issue and ensure to have people with good customer service and who are really sensitive to people's concern.