I understand your frustration, but I also think they have a point.
What you're telling us is all based on your educated guesses as to how they might have pulled this. There are things that feel a bit weird and I'm guessing you have no evidence to prove them, such as the scammer shipping the real SIM back to Atlanta in time before you realise the issue.
How did you realise the SIM card you were handed was fake? Couldn't it be that they instead duplicated your SIM whilst you weren't looking?
IMHO the police (or FBI or whatevs) in the US should conduct the investigation as that's were the fraud happened. They'll evaluate if it's worth it contacting their counterparts in the UK to move forward. However I also think it is good that you've given a heads up to the UK local authorities.
Do you remember what company was offering the local SIMs? I've seen mostly Lebara, but not in Heathrow...
The SIM ICCID that I physically had in my hands upon return was different than the ICCID that ATT had on file for me. I also watched the dude do it right in front of me, but of course SIM cards are quite easy to palm. It was the "Tourist Services" kiosk and I bought a £20 Lebara card. He very kindly taped the ATT card down to the Lebara cardboard packaging, and I wasn't able to remove that tape without damaging it so I'm quite certain that it wasn't swapped elsewhere.
I did also report it to both my local police and the FTC and the FBI but never could gain traction as nobody thought it was their jurisdiction. I eventually gave up once my credit was repaired.
Just playing devil's advocate, the ICCID on file would also be different if they had managed to compromise your account and change the sim associated with it.
That might be reasonable. It also makes the scam OP is guessing happened a pretty good criminal scam, since the police will refuse to investigate it...
I mean, what possible additional evidence could one plausibly have that the guessed scam is indeed what happened?
Which is the scary thing about all these SIM-theft things. It clear happened, there's really no way for the victim to know how/where/what/when/who.
It certainly took me quite some time to put all the pieces together — and I'd wager very few folks defrauded like this are able to realize exactly what happened.
What you're telling us is all based on your educated guesses as to how they might have pulled this. There are things that feel a bit weird and I'm guessing you have no evidence to prove them, such as the scammer shipping the real SIM back to Atlanta in time before you realise the issue.
How did you realise the SIM card you were handed was fake? Couldn't it be that they instead duplicated your SIM whilst you weren't looking?
IMHO the police (or FBI or whatevs) in the US should conduct the investigation as that's were the fraud happened. They'll evaluate if it's worth it contacting their counterparts in the UK to move forward. However I also think it is good that you've given a heads up to the UK local authorities.
Do you remember what company was offering the local SIMs? I've seen mostly Lebara, but not in Heathrow...