Hi, I’ve been handling this incident from Monzo’s end.
There are two related issues we’ve seen:
- Yesterday something went wrong with TfL’s billing system around 5pm and they authorised a large number of customers twice or more (I’ve seen some users who got three) for their travel on the 12th (This is really unfortunate timing from the perspective of us trying to get through to someone at TfL or their acquiring bank to notify them of the issue )
- For Apple/Google Pay transactions, Mastercard’s systems detected that they were replaying the same tap and declined these transactions. In addition, a smaller number of people might have had transactions declined for other reasons, e.g. a frozen card or insufficient funds.
- When TfL receive a decline, they normally block that card (or virtual card). We thnk that as a result, people who’ve had declines for the duplicated payments may find that the ticket gates decline their cards/phones today.
Other than the issues people who’ve encountered declines have had it appears their systems are operating normally now, and where we could identify transactions that looked very likely to be duplicates we’ve reversed these and released the funds back to the affected users.