Hi @Влад666, let me see if I can help out here.
Your post has been translated to English as this is an International forum, please post any replies in English and it will be easier for me and other users to assist you.
Have you been able to try another headset with your phone in order to see whether the phone works better with another headset or not? Also, try cleaning the headset jack with a wooden or plastic toothpick to keep the jack free from lint and grime.
Another thing that you can try is to reboot your phone in safe mode to see if the headset works better there. All apps downloaded from Play Store is temporarily deactivated while in safe mode and by doing this, you can see if this behaviour is caused by a downloaded app. For more information on safe mode and how to use it, click here.
If the behaviour of the headphone jack persists in safe mode, my suggestion is to try to repair the software using a computer and Xperia Companion. Keep in mind though that a software repair will erase all user data from the phone, so make sure to do a backup of your user data before the repair.
If none of these measures manages to improve the functionality of the headphone jack, I suggest that you get in contact with your local support team in order to have your phone sent to an authorized service center to be examined and possibly repaired. If you have any questions regarding the service such as routines, warranty and consumer laws, these kind of questions are best answered by your local support team as well.
Try these measures and let me know how it goes!
