Charged with a £100 penalty for not providing tax return, I claimed from removal before though

Hello. My name is VIKTOR NAZARUK  I worked for delivery company UBER EATS part-time by my bike during the lockdown 2020-2021 and earned less than 200 pounds being self-employed for this certain year. At my personal account on the gov.uk site I checked if I needed to send my Tax-return using "Check if you need to fill in a tax return". System notified me that "you do not need to send a Self Assessment tax return". Then I applied and send a request by email for removal from Self Assessment for that year on 5th Decembeb 2021. I was promised to get a response within 15 days, but never had it. Some days ago I received a message on my gov.uk account that I've been charged: "We've charged you a £100 penalty because we didn't receive your tax return for the year ended 5 April 2021 on time. You'll need to pay the penalty within 30 days of the date of this letter. We charge interest on late payments." I called the specified number on the email to figure out what's going on but the answering machine sent me back to the site. Could, please, help me. I don't need to send a tax return and I want to let gov.uk know about it and appeal my penalty after. Thank you

[Personal information removed - Admin]

Hi,
 

Self Assessment tax returns are issued by HMRC for a number of different reasons. A late-filing penalty is automatically imposed if you miss the submission deadline. Please now complete and submit your 2021 return as soon as possible, even if you think you don't meet the Self Assessment criteria. You can appeal against the penalty if you have a reasonable excuse. Thank you.