7 days is starting to get a bit long, but not a disaster yet.
The person who sent the money should at this time contact the sending bank again.
At the moment the money will be sitting at the correspondent bank in England.
It will take them time to send it back to the US bank, and then it will take time to return it to the sendor.
You say the IBAN "didn't exist".
Did the sendoer send it to
- the correct destination bank?
- the correct SWIFT code for the destination bank, if they gave one?
- the correct account name ... and address etc?
You don't have to give an account number. It's a manual process. It's not inconceivable that after some verification the money will reach the receivor.
"information I was able to dig up online specifies it usually takes 2-3 days...
So, people who spend time writing on the internet, are idiots : I have never, ever, seen a send-back done in only a couple days.
It is not panic time yet but sendor should certainly now ask BOA again, and seek specific details. ("Where is the money >now<, does the correspondent bank still have it?" etc.)
One thing that will cause huge problems is that, the staff at BOA (or any bank in the US) who handle wire transfers know, literally, nothing at all about wire transfers. When I say "nothing" I mean "absolutely nothing".
So it is always an uphill struggle.