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.