Hi Tomasz Ullman,
Thank you for your question.
I would like to state that we are currently working postal items in date order to ensure they are dealt with fairly and as effectively as possible.
I would advise for further information on you personal case to use the attached tool which may outline the date that is currently being worked and when to expext a reply from HMRC:
Check when you can expect a reply from HMRC
You may also wish to use your Personal Tax Account if you sent the Form 17 in online.