DHL doesnt accept responsibility for cheating

I am a student and I had sent my mark sheets to a few US universities. I had approached this person in LB Road Chennai who had a DHL sign board outside his office. I went and asked him if he was the official DHL and he said yes. I asked him for the rates and he said 2700₹/ parcel. I agreed and I sent five parcels. Later I got to know that DHL offers students an offer by whch they are required to pay only 950₹/parcel. I went and asked him why he didnt inform me about this and he said 2700₹ was “His rate”. I made a friend of mine call him and ask him the rate. When my friend called he said the rate was 950₹. He didnt inform me about this offer. I have been charged almost three times the actual rate. I took this issue up with DHL and they do no seem to be cooperating. Mr. Benoy in the customer service DHL seems to be very ignorant. I called him up and all he said was “We cant do anything”. The person is in fact a DHL dealer. He is using their name. And he happens to have all the DHL airway bill numbers. I don’t understand how DHL is saying they are not responsible. I feel this is downright outrageous. I have proof of the same person saying that the rate is 950₹ and I also have the receipts in which he has charged me 2700₹. I would be happy if appropraite action is taken against this.