Chrome Version       : 69
OS Version: Mac OS
URLs (if applicable) : https://www.s7.ru/

What steps will reproduce the problem?
1. Book flights on the S7 website
2. Fill in your passenger details using auto-fill
3. Open payment form. Note the form with passenger details still stays on the page.
4. Fill in credit card details using auto-fill (the card belonging to other person)
5. Some fields are wrong - fix them manualy (also using autofill suggestions where reasonable)

What is the expected result?
The fields that are already filled in are left untouched.

What happens instead of that?
Autofill changes values in the passenger details form, which is on top of the page. I didn't notice that, and as a result, we booked tickets for my name instead of my wife's (the card was mine). We needed to call the S7 hotline and send them a copy of the passport to change this, and they told us this is an exception, normally name change is not possible.

Sorry I don't have more technical info on this, but I could try to recreate the scenario if my description isn't precise enough.