Credit card fraud alert?

Not Britrail, but I spent a few hours trying to buy a Swiss Rail Pass from SBB.com, got a code texted and all, but then it said "unable to finalize payment" or something. Using Firefox on Windows. Tried using cable internet and then cellphone hotspot internet. Tried 3 cards. Finally gave up and bought the Passes from Eurail. No problem with them.

I think the problem is with the payment processor that Britrail uses... Maybe doesn't like my I/P addresses? Or Firefox?

We have that happen in various countries when trying to purchase train tickets. Last time it was Renfe the railroad in Spain. We ended up using PayPal. Order went right through.

I’ve had this happen and rail tickets are one of the places where I have experienced failures. In particular, at least once or twice every trip over the past couple of years, a purchase on my Chase card fails. 3-D secure has been the culprit a couple of times. If you got a code it doesn’t sounds like that was the issue but the transaction could have timed out. When the purchase has failed, I’ve been able to make the purchase using my Citi card or Apple pay. If you don’t have a different card to try, I’d call the credit card company tomorrow to see what happened. I recall one time (years ago), the card company had to unblock something for the charge to go through.

I'd also try a debit card.

I had this happen in Rome, both online via a browser and via the Trenitalia app. Card got denied, VISA sent me a fraud alert (even though I had been in the country for over a week and using the card), and it took a few phone calls to get it all straightened out. Luckily we were not far from Termini, so we could walk over to a kiosk and use a different card to get tickets. Also had issues with Renfe in Spain, so used Trainline instead, which was much easier anyway. Something about train apps maybe?

Did you tell your bank that you were going to make it international purchase? If not, that’s probably why it was declined.

I use Paypal to purchase train tickets from the operator's websites in the UK. If you have an account there and the site you are using accepts it a means of payment, that avoids any shenanigans with foreign credit cards being declined.

Related to what Robin said: telling your bank or credit union that you are away with a “vacation alert” may help. I had to do that (even though I was in the states) in order for my ETA to be processed.

Not sure it works for a rail pass, but using a site such as trainline is one of the few times that a 3rd party site may work to your advantage, as they have probably dealt with all of the payment methods, and have a motivation to keep it that way...