Fined £100 by HMRC for not submitting a tax return I was told I didn't need to submit

[Peae]

Last year I rung HMRC and they confirmed I didn't need to submit a tax return for the year ending April 2023. This sent me a reminder around December, so I rung again, and told not to worry about it. It was a general message for people who did and could be safely ignored. I asked if I needed anything in writing, and they said no.
Now I've received a message saying I have a £100 fine for late submission.

Any advice or experience? I feel pretty angry and frustrated, but not a lot I can do now until Tuesday.

At the end of my work career I set up a company to do some self-employed work, When I retired four years ago, I closed down the business officially. Now my only income is the State pension, and a pootling amount from bank interest. Nevertheless, I kept getting these letters telling me I need to fill in a tax return. I got my old accountants to do that for me. This year, when I got a letter in April, I contacted my accountants again, and said, do I really need to keep doing this? They said, don't do anything; we'll contact HMRC on your behalf, and see if we can get them to drop it. Few days later got another email from them saying, it's OK, HMRC agree you don't need to do it. Which I thought was pretty decent of the accountants, because effectively they are losing my business now. So all good, I think. But interesting to hear how commonplace this is.

Okay but I managed to sort mine out via chat

If you're not due to complete a return then you don't need to appeal against the penalty you ask HMRC to cancel it as it isn't legally due.

I've done it. 2 hours sending 'advisor' on the online chat and then almost 30 minutes chatting with the advisor. She cancelled the penalty and I have it in writing now. (She was really good, slow but very personable and human).

They really don't make it clear on the website what one should do. Fingers crossed that's the last of it for me. I hope everyone else's problems get resolved soon.