I flew AI173 DEL-SFO on Dec 31st in paid Biz (Z fare ticket). At the gate, after scanning my BP, agent told me I was upgraded to F and simply wrote the new seat# on my existing BP. It was a system upgrade as Y was over-sold so they upgraded a few folks from Y to J and at least I got bumped to F.

So I board the plane and take my seat (2K), happy to get a flat-bed on this 16hr flight. F was completely full, and there was an Indian lady travelling with her young kid (may be 2-3 years old) in the first row middle seats, though both were sitting on the same seat. While I'm enjoying my pre-departure champagne, another Indian lady comes and starts arguing with her. From what I could get, she was trying to take her kid's empty seat, but then goes away after their argument gets a little loud.

After a few minutes, the flight supervisor comes and asks for my BP, takes a look and goes away. Then he comes back with a ground staff, who tells me that my seat has been reassigned and I have to go back to Biz. A bit surprised, I try to inquire about this change, but they just say it is through the "system". Dejected I take my stuff and go back to Biz. And worse, due to the upgrade I lost my pre-selected Biz seat and had to take the last available one. Even as I'm moving my stuff, the lady who was earlier arguing with the other lady in F, comes and takes my seat.

After take-off I try to find out more about this downgrade and luckily see the business class manifest hanging in the galley. I see that my name is not on it and the seat I'm on, is assigned to a Mrs Singh (later confirmed to be the lady who took my seat in F) and that she had a R-class ticket for business class. If I'm not mistaken, R-class is a non-rev ticket given to employees (can someone please confirm). So I ask the FA about this and he says to talk to the flight supervisor who at that time was taking his 5hr rest and will be back later. After he comes back, he says that he doesn't know anything about this but that the ground-staff lady who was a handler from SATS (the company that handles the ground operations for AI flights at Delhi) had asked me to move back to Biz as the request had come from "commercial" and there was nothing he could do about it (which most likely is not correct). I ask him to show the manifest that has me assigned to the biz seat. He says that they don't have it since the change happened at the last moment and it would have taken 20 minutes to get a new one, which would have delayed the flight. The flight supervisor was a very nice guy and apologized profusely for the confusion and trouble, but I could make out that he was aware of some shenaningans going on (hopefully not on his part).

Based on all the info I have, it is quite certain that this lady (Mrs Singh) either had some connections or may be had bribed someone to get into F and basically I was forced to give my system assigned F seat to her, while I had to take hers. The fact that she was on a non-rev ticket and that earlier she was trying to take the kid's seat are pretty good indicators.

I'm going to report this incident to AI (still have to find the right venue to do that), but wanted to get thoughts and inputs from AI experts here.

What would be the best way to report this incident so that it doesn't go unnoticed and at least there is some inquiry into it? Has anyone else had a similar experience on AI?