Wondering if this is a regular occurrence.

My partner and I flew GLA-LHR a few days ago on an avios booking. As a gold BAEC member, I selected seats when I made the booking a few weeks ago, and reaffirmed the choice when checking in via the app.

Upon entering the lounge, the agent asked if I was flying Club (?) to which I answered no. Then she asked if I had changed my seats. Eventually, she concluded our seats had been reassigned because the Club cabin was extended to row 6 where our seats were. It was an A319 and we were moved to the twin seat in row 25 next to the toilet and without a window. I protested but the agent wouldn’t have any of it. I then raised the situation again at the gate and the agent recommended that I reserve my seats next time, so I didn’t bother engaging further.

What ticked me off the most was the lounge agent’s response to my request to consider swapping us with someone else. Yes, I did pull a DYKWIA and highlighted my status. She said it was pointless to try because all of the plane passengers might have a gold status, as well. She also implied it was too late.

Of course, it was tolerable - took maybe 5min longer to exit the plane, obviously there was no immigration, but I had no access to BoB given the short length of the flight. However I can’t help but wonder if this is all normal and in policy? I did raise a complaint and am waiting to hear back.