Indigo Airlines — Very rude customer service at Mumbai airport

Hi, I live in the US but recently visited India (I am originally from India) and make trips often. Most of the times for local flights, i fly other airlines like Vistara and in the past Jet airways etc. This time I flew Mumbai to Chennai on Indigo and flying this career for the first time. This easily has been my worst experience till date. I am in Sales and so flying (mostly within the US) and international is a norm for me. I had to carry a little extra luggage with me - 1 KG over the 15 KG allowed and I also had my family travelling with me (wife and 2 kids) - Each of our check-in bags was 1 KG over the weight limit. Since we fly international, it is hard for us to not carry a lot of stuff - International flight baggage limits are 23 KG normally. I thought this would be okay since the flight was half empty and I explained to the agent at the airport 2 things - One that i am flying internationally and 2, that i also have a student flying with me but i did not choose the student fare option while booking (which allows 10KG etc for the same ticket price) - The agent was super rude and said they cannot do anything and asked me to pay the fine. I had called the customer service desk the previous night and asked about possibly changing my ticket category to Student but they said it cannot be done post booking. After speaking to a supervisor, they said they will put a note in my PNR about allowance for extra KGs but that its not guaranteed to be accomodated. When i mentioned this to the gate agent, he looked at the notes and did see this and called a supervisor to see if they can do anything about it. Sylvira was the sypervisor that came to talk to us. She was even more rude and asked us to weigh all our handbags. Our handbags also were a little more than the allowed 7 KG per bag. So instead of the original fine of 4000 rupees or so that the agent had asked me to pay Sylvira said we need to now pay 15000 rupees! All this because i requested them to read the note and see if they can accomodate us. I was obviously stunned by this and asked if i can speak to someone else as this seems like daytime robbery - Another superviser Yolanda then came and was more rude. She said we will miss our flight if we keep talking and that we either pay up or leave the place! All in all, i agree we had some extra weight in our bags but the treatment given to us was appalling. This is 2 days after our Indigo flight from Agra to Lucknow was delayed by 2 hours resulting in us missing our Air Asia connection from Luckknow to Bombay resulting in us losing money on both the flights. Overall, Indigo because they have a big marketshare seems to not have an iota of customer focus and has left with a horrible experience and i will never fly indigo again for local travel within India