It’s only happened once to me but I’m going to note it since it’s never happened to me on my regular debit card.
In Waitrose.
Till reported ‘card declined’, even though it showed up as approved in the app, had the notificiation etc. This was about 4:30pm Sunday.
Tried a second time and it worked, when the new transaction appeared, a third refund one reversing the ‘failed’ first one appears too.
I had the same thing happen at a restaurant near work. Second time went through perfectly.
I had this happen at Boots, declined twice. Didn’t try a third time.
Thanks for the reports! We think this is happening because of a timeout somewhere in the process (hence why it often works the second time) and are going to look into why this is happening and see what we can do about it. I’ll keep this topic updated when we make progress 
Just to chime in, I got this today in Sainsburys too. Amount taken, amount refunded. Second attempt fine.
I got this at my local swimming pool cafe on Saturday (2nd Jan). Second time it worked fine. First time it’s happened to me.
I had this too - I wonder whether there are two separate things here:
If the authorisation message didn’t get back to the terminal before the timeout then you should expect to see an authorisation followed by an auth reversal (which will appear in your feed as a payment followed by a refund).
We have no way of telling that the initial authorisation didn’t get to the terminal until the auth reversal comes in as the messages are all asynchronous. A traditional bank only shows you transactions after they have settled (much later) and therefore would never show the first auth as it would never be presented for settlement. Some terminals are poorly configured and don’t even send an auth reversal and for these the auth will expire (usually in 7 days).
There are two things we can do:
I think Mondo could improve its behavior lot in a few cases which currently result in multiple transactions. Mutating existing transactions to correct the actual outcome should happen in a lot of cases, in my opinion.
Just had this happen again in Co-op. Both contactless and chip and pin declined. Amounts appeared in mondo feed then refunded.
This has never happened to me with my Nationwide account, which I sadly ended up having to use.
Wonder what can be done to stop this issue? I was made out to be a common criminal because I put my lotto ticket in my wallet before cleared payment!
Thanks for all the reports! @anon73816237 is planning to look into this first thing on Monday morning so hopefully we’ll have more answers later next week
Great stuff! On that note - when getting a refund, can the “Spent Today” be updated to reflect that?
Yes, we’ll update the “spent today” properly soon
This also happened to me. It was because the merchant’s card machine was playing up. But because of the delay between it appearing as having gone through on the phone, and then showing as being refunded it did cause a minor argument. The merchant was showing it as having declined, while I was showing them it went through on the phone…
Don’t know how much use this is, but it’s happened to me twice now…once in a fast food restaurant with a big M logo where it seemed to cause the ingenico card reader to malfunction and crash and another today on a portable Great Western Railway card machine, however the portable card machine just didn’t like the card.
I had a terminal crash on me at a Copenhagen train station last weekend after a decline too