My Tandem card didn’t work at Superdrug. Declined and ‘we suspect fraud’ in-app notification. Given there are lots of cards that don’t work at Superdrug (old Monzo cards didn’t, Amex doesn’t - though that’s a different issue, etc). I decided to peek through the logs on the card. The one difference I notice is in the second byte of the CVR for the Superdrug attempts. It’s 00000000, whereas it’s 01000000 for all other contactless transactions.
If my Google-fu is on target today, that translates to
Combined DDA/AC Generation Returned In First Generate AC - now, I’m by no means a card or EMV expert, but could this be the cause of Superdrug compatibility issues? It looks like they’re not completing data authentication? Is that correct?
Also, a thumbs-up to Monzo. While these kind of thing may be rare in Britain they’re common in other countries. While Monzo may not like American/Israeli Coke machines and their infamous CVC mismatch, they do work in almost any other situation - including PayPass magstripe mode. Tandem’s a ‘travel card’ but it can’t even handle Superdrug?