Self assessment - not self employed - have I been hacked

Hello, I have received some late filing fines, I have never been self employed. When I tried to log in to gateway id that I haven’t used for about 10 years it said that I had another id and the email listed on it is not mine, it also said I logged in last august which I didn’t. Is there a chance I’ve been hacked? Also I have no investments and have never been self employed what could the reason be for this tax return as I now have a £1200 fine

Hi,
We would need to access your record to check why the tax returns have been issued.
You can contact HMRC:
Self Assessment: general enquiries
Thank you.