[Resolved]  Indigo Airlines — seat assignment

Dear sir, we are senior citizens and get a discount on some airlines, but we still travel on indigo due to its on-time performance and clean planes. I travel on indigo quite frequently.in my last two trips i had problem with your seat assignment process.
I travel with my wife, in my last two trips we purchased our tickets well in advance. We both were on same pnr. We checked in on line the night before. As a common curtesy one would think that the two seats will be assigned side by side. We were both assigned middle seats in two different aisles. At the airport, while checking in, i requested the agent to assign us the two seats together, but she without even bothering to look told me that the plane is full and the two seats together are not available. When we got in to the plane there were several seats available. As a matter of fact the seat next to me was vacant. It happened to me on both legs of the trip.
I wonder what your seat assignment process is?. Do you keep them to your preferred customers. If so what does it take to be your preferred customer?
My complaint is that your check in agents are not courteous and are not doing there job. I am a frequent international traveller and must have flown well over four million miles, but had never had that happen. The check in agents are normally very considerate and go an extra mile to help the customers. My experience with indigo was very different
For your reference my pnr number was lb7cnc. It was delhi-mumbai-delhi flight on april 3rd and return on april 9th.