I have been moved a number of times in the past 9 months.
Not happy about it ... and I believe it is staff trying to help out a friend. Not good enough.
And for those that have been moved to a worse seat for a higher status member. That is shocking and should never happen. Chairmans Lounge or Platinum One. If a seat is taken it is taken. I would never want someone moved out of their allocated seat to accommodate my preference.
I had this done to me occasionally, but never bothered to investigate until last Friday (26th July 2013) when flying LHR-PRG (BA). I only booked it on the Wednesday and was very pleased at bagging 4A For those that don't know - there is no 4B on this A320 conifg and they essentially the same size etc of business class seats with extra legroom. Then when I went to checkin - suddenly my seat was 5A. I was only mildly annoyed until I phoned BA and politely asked if there had been an aircraft or configuration change (I *think* the J curtain can be moved to incorporate row 4 if needed). Answer to this was no. so I asked if someone with higher status had been allowed to take the seat, or perhaps a medical reason? (someone with special needs?). What I was told next annoyed me enough to not be able to just let it go:
I couldn't believe my ears when I was (in no particular order):
1. I had made the change from 4A to 5A myself.
2. Someone else on the booking had made the change (I was the only one on the booking!!)
3. "They don't make changes like this so I cannot remember correctly" (WTF?)
I saw red after being accused of lying, so I asked to talk to the manager on duty and incredibly I got the same BS stories.
I was ready to give up and was noting done their information ready to make a pointless complaint to BA customer care (for their bad attitude and accusing me of lying, not the seat change). As part of trying to be thorough, I asked the "manager" to at least let me know exactly what time my seat was changed "for my records" - a few more minutes on hold and I found out "The seat change was done at 21:52 by someone in London, if you want to find out why you will have to talk to them tomorrow."
So - an admission that they made the change (finally) but no apology - nothing. I pity anyone who needs real help from BA after hours and gets the same two that I did. (and don't care that they were based in India, that doesn't excuse their poor attitude).
I sleep on it and call again in the morning. this time I get a middle aged (and unfortuantely, very surly) english woman - short conversation "your seat has been changed for operational reasons and it is now a protected seat, you cannot have it back. We do not guarantee seat selection." At least she was helpful enough (despite being really surly) to find out the following:
1. The change was made by "Load control" at 21:52
2. the actual notes on the booking said "Operational Reasons"
unfortunately, that is pretty much as far as it got - any questions (no matter how politely asked) was responded with "We do not guarantee seat selection." then she accused me of trying to get a "free upgrade" (something I wasn't interested in - she even confirmed 4A wasn't in business class.
I get to the airport 3 hours early and checkin. I simply said "have you guys changed the aircraft, really odd that my seat was just changed - could you have a look why please?" to which he agreed, I continued "look, it isn't a big deal, but something doesn't seem right, this was done at 21:52 and fair enough if a OW Emerald or whatever has been given priority, I am OK with that, but I just want you to make sure it isn't some non-revenue passenger or "friend" of BA Staff that has "taken advantage".
Ahrooj (name of the guy at checkin desk). Agreed that it looked VERY suspicious - the following was confirmed:
1. No Aircraft change
2. No Config change
3. Person "moved" to 4A had no status.
4. It wasn't a "paid for seat" (BA charge a seat selection fee for non-status pax, sometimes this can override a "free" seat selection)
5. No special needs pax were on the flight at all.
6. There were no issues with load requiring pax to be moved for aircraft trim.
I think he said something like "what you suspected might have happened". He then picked up the phone to someone and said "this operational reasons excuse is not good enough and you are to give this person back 4 Alpha." I got an apology and the promise that there would be an investigation. I then found out BA have change their rules and OW Ruby now get fast track! - that cheered me up immensely.
TL~DR
Staff will "bump" you out of the good seats for their friends. It probably happens all the time. It defintely happend to me.
A few queries in a search engine will confirm that some airlines get away with this more than others.