INDIGO IS FRAUD AIRLINES!!!!!

It is about 18th Feb 2017, i was returning from Hyderabad Rajeev Gandhi Airport when
i faced this Fraud. I have a habit of weighing my luggage prior to travelling in flight and even this
time i have already weighed my luggage which was under 12kg and 7kg handbag approximately. I was already late for my flight and when i entered the immigration department
and sent the luggage for weighing they said my luggage was 15kg extra to the free limit i.e 27Kg. I knew my luggage was only 12kg and when i said them, they didn't agree and forced me to either pay the extra luggage amount or leave the luggage with them and go.
But i was right and i didn't fear proving and so i argued that's when they told me either you pay or you'll lose the flight, there's no other option. They feared me and thus forced me to pay and i had to pay 2600 INR. I have a receipt of it which i am attaching, you may see.
I have travelled through various airlines but something like that never happenened with me. This was the first time i travelled in indigo and got this worst experience. Never trust this airlines, ALWAYS WEIGH YOUR LUGGAGE PRIOR TRAVELLING TO INDIGO. This makes me think how huge amount the airlines is making through this scam if only it chages 2500 INR extra to each passenger.
PLZZZ BEWARE.. I was late and helpless so coudn't do anything but never get trapped in this INDIGO WEIGHING SCAM!!