Have you considered going to a branch office and telling someone in person?

@MichaelKjörling that would be possible if not particularly convenient

How about a phone call?

You think this is bad, I get mail for a former occupant from Companies House, who tell me "As this address can only be changed by the company, I will try and contact an officer of the company to arrange for the required notice to be completed in order to update the address" !

@PeteB., that's what I meant by "should refuse to discuss..." -- they probably shouldn't even confirm or deny the existence of a customer with that name.

"Hello Mr. Banker. I am getting mail for Joe Smith at my address. He no longer lives here and has not within the last 10 years. I have no knowledge about their address." They discussed nothing.

I had a bank send an online account password for someone else to my house. It was a pain to work through their phone tree to finally get ahold of a live person but when I did and explained the situation they thanked me profusely for letting them know. There hasn't been a recurrence.

@PeteB. but did it acheive anything?

I had deposits made to my account that were clearly intended for someone else. IIRC it was an employer-related account so the other person was a fellow employee, but I didn't have any way to know who it was. I contacted the financial institution by phone. It took them a few months but they tracked down who was supposed to be getting the deposits, or at any rate they stopped putting them in my account.

@ChrisH i think it was a suggestion, but i can't think of any reason it would not work

it sounds like you are re-packaging the mail. instead, just write "return to sender" on the envelope and drop it back in some mailbox. that way, the bank will have to pay the return postage. oddly enough, charging them even a few pennies tends to motivate banks to fix their problems (what get's measured gets managed). besides that, it makes the mail more likely to be routed to the correct department.

@jamesturner, I'm doing as you suggest, just writing "Return to sender. Moved away 2006", and there is a return address on the back

@AytAyt I'm not a fan of wasting my time sitting in a phone queue for ages just to get through to someone marginally less incompetent than the front line staff (who seem to be forbidden from being competent however willing they are). My dealings with that particular bank are very limited, partly because I've found their customer service so poor. But with some encouragement I could try

@jamesturner Actually, I don't think that's the case in the UK. The returned mail is simply returned at no extra charge.

@ChrisH, so you prefer wasting a few seconds year after year to taking the 5-10 minutes it would take to solve it once and for all? I guess that's your choice. As someone who has worked in customer service, everyone thinks the position means you aren't competent, but I think it's more that the customer doesn't understand the policies and procedures that the customer rep is required to follow. Perhaps it's the same in your case. It takes another step than you are taking. So you have the choice of deal with it forever, or once, and it's up to you.

@AytAyt no, I'd rather not waste any time every year. But my experience with phoning up some companies including this particular bank has been than I can write a letter, print it, and walk to the postbox in less time than it would take to get through to someone who would fail to help. If they can't or won't pass me on to someone who can help quickly (when they eventually pick up) either they're useless or the system is. I don't care which.

Nowadays, the seemingly most productive course of action is to shame companies over social media. "How incompetent is BANK X? They've been sending me the old homeowner's statements for the PAST 10 YEARS and won't fix it. ARRGGGHH!"

@ChrisH I guess it's just a difference of locale or people we're dealing with. For me (and I have had to deal with this, I work for a company that flips homes, so lots of previous owners during the build), I just call and politely ask for someone to help update their files. I kindly describe the problem, and it's solved. usually 5-10 minutes of actual talking, with another 5-10 minutes of wait on top, so 10-20 minutes total I guess. The key is to be really nice to them, and suck up a bit. I've never had someone fail me.

@ChrisH didn't you say you HAVE been sending the letters back? So why would writing a letter do anything new? You "return ... them... with a note" but that doesn't work, thus the suggestion to call, try something new. Or are you saying you HAVE called? I didn't see that in the OP. I also don't see how there is any frustration or confusion to "hi can you connect me to someone to update your records?" wait a minute "the previous owners have moved, can you update their records and stop sending mail here? Thanks, bye". That's all it ever took me.

@ChrisH If you want to continue, we should do it in chat