Passport vs I551 Name

[KDance 1]

Hoping someone can shed some light here

 

My passport is in my old name.  My Green card is in my new name (expired).   I have an i-551 extension stamp in my passport and it has my Greencard name written on the page by the USCIS officer.

 

I am trying to check in for a flight home to the UK and it asks for my Green Card details.   

 

Should I enter in the I-551 details?  So the last name is different to my passport and the new expiration date (the extension date given).

 

I've tried calling USCIC to ask but just go in circles with the automated phone system

[Hypnos 6,576]

Enter the green card name as the I-551 name they wrote in your passport.

 

Your travel itinerary should be in your passport name, however. and you should carry a copy of your marriage certificate to document the change.

[KDance 1]

Thank you for your help.