How might this credit card fraud have happened?

[weaselyeyes]

I have 4 different credit cards, which I use for different purposes to keep track of spending. I pay them off in full each month apart from one which is a 0% balance transfer, which I'm paying off in chunks. Two of the cards are with the same provider, the balance transfer one (A) and another which just has a couple of small regular subscriptions and is also linked to my paypal (B).

I had a message querying a transaction for about £50 on card B which I didn't recognise, and a follow up call about it today. It was to some account in Brazil, nothing recognisable, so they said they'd block it, refund the amount to my card and send a replacement. They mentioned there'd been two attempted transactions. Then they rang back to say the second transaction had actually been to my other card with them (A) and had been blocked outright and they'd also have to replace this card. This seems really odd. The first one just seemed like one of those things that you can't get to the bottom of but has been resolved, but two cards simultaneously seems strange, especially as the second is never used for purchases. I have the cards, haven't had them out of my sight or used them for anything other than the above purchases/payments (all online), and don't live with anyone other than my daughter, who's currently home from uni and wouldn't be involved. It's made me feel anxious as I'm not sure what I can do to safeguard further fraud if I don't know where it's from. All 4 cards are kept together and I there aren't any other odd transactions (yet, anyway!) on the other 2.

It sounds like you have been skimmed, in which case all your cards may be at risk. There are small machines that only need to be in proximity to your cards to copy the details. I never keep all my cards together and every holder /purse I use has an RFID blocker now.

I have also read that if you keep your cards in a digital wallet, getting access to one card can allow scammers into your wallet - I don't use a digital wallet, so I am not sure how, but I seem to recall someone posting about this only a few days ago.

@PhilippaGeorgiou Thank you, I wondered if that might be it. Interestingly, I have my other two cards and my debit card in the wallet on my phone, but not the two which have been targeted, as I never use them for on the spot purchases. I wonder if the fact they're with the same provider means they have different security somehow and are less resistant to skimming? I definitely don't have any RFID blockers on purse, though, so that's something to look into.

I am now somewhat obsessively checking my other cards for transactions.

We're the cards Capital One? I had similar last month. There are data breaches all the time, I don't carry my cards around, dodge ppl buy data from other dodgy ppl can be anywhere in the world and apparently can buy apps that try loads of passwords with zero effort then bingo if they get lucky. I have also had Netflix hacked twice in last month by South American hackers. Also had Amazon problems when I don't even shop with them and Vinted. Just keep close eye on all transactions. Luckily like you most were blocked before goods were obtained.

No, they were Barclaycard, I've had a handful of random problems in the past with various accounts and cards, but this just stood out for being two different cards at once. I suppose if there are data breaches from companies, they're not always publicised.