Incorrect address - HMRC changed this without my knowledge into an address I am unconnected to

I just logged into HMRC to do my taxes for 23/24. I have discovered that my address has been changed into an incorrect one, in a different postcode, that I have never lived at! I had nothing to do with making this change - the last time I was on the system was about a year ago, when I submitted my Self Assessment for 22/23, and I can see from my records that my address was entirely correct on that. I expect an HMRC agent will respond to this post saying I can correct my address on the system - but that is not true. I have tried, and HMRC will not accept the true date at which I moved into my address (which was decades ago!). Instead, I would need to pick some random date, more recent then the date (unknown to me) on which my personal information was altered. This is unacceptable and I want to know how this could happen. How can my personal details be altered by anyone other than myself? From a quick browse of the forum, I can see that many other users have discovered the same thing. This is shocking. However this has happened, HMRC needs to fix this urgently. I would like to contact a GDPR specialist at HMRC about this. I wish to insist on my details being put fully correct, as is my right. And that should not include having an entirely fictional period on my records at which I lived at some other address. I also want an answer as to whether HMRC has been sending physical letters to that address.

Hi,
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