Phone trade in

Hi all ...

my wife recently sent her old iphone away for cash... ,then received an email asking for her Apple ID and password. I thought that was a bit dodgy so went on find my iPhone to switch off iCloud .. which I did !! Then she tells me she hadn’t erased the phone either!!!

so now I can’t use find my iPhone as I switched of the iCloud ??? Is there anything also I can do?? Hope this makes sense.

any help would be greatly appreciated 👍🏻