Hi MitkoVIP,
Thank you for the response and updates. I'm sorry to hear that the issue persist. You should not be having this kind of issue considering that the headphones are new and this is likely a hardware issue on the headphones already considering that it occurs when connecting either your iPhone XS or Surface Pro 7+. I suggest having the headphones replaced. If it was ordered through the Microsoft Store, please contact our live Microsoft Store support team and have a return, refund then repurchase. See: Contact Microsoft Store Support.
You can also contact our Surface Technical Team and they could then transfer you over to the Microsoft Store support. You may contact them through the numbers listed in Global Customer Service phone numbers (microsoft.com) under For Business users. This works with Home users also, just select Surface then Home as a type of user in the IVR prompt. You may also reach them through this page: Contact Us - Microsoft Support following the steps below:
1: Go to Contact Us - Microsoft Support and sign-in your personal Microsoft Account
2: To make sure you are using the correct locale of the page, click the Globe icon on the lower-left corner of the page then select the country you are in.

3: Click Get support

4: On the Describe your issue box, type in Contact support then click on Get Help

5: Click on Contact Support at the bottom

4: On the next page, select Surface then Technical support then choose your Surface model and click on Confirm

5: These options should appear depending on which is available on you country. It would also show the available time of support if in case you accessed the page out of the time of operations.

You may select **Provide your phone number and a support agent will call you** option and you will be ask to select and confirm your phone number then click **Confirm**. You will then receive a phone call from support in a while.
Selecting **Chat with support agent in your web browser** will ask you to confirm the email address associated with your Microsoft Account then click **Confirm**.
Kind regards,
Marrion