Do I get a prize for being able to take my Mondo account overdrawn?
The tipping culture in the US makes it possible to go overdrawn on your card: You pay for a bill (meal, drinks, whatever) and your card is authorised for the total amount. You then write your tip on the receipt and at some future point the transaction is reprocessed with the total+tip amount.
To illustrate an example: Lets say you have £70 in Mondo balance, which equates to $100 at today’s (miserable) exchange rate. You get the bill for that nice meal and cocktails you had and it is $90, before tips. You hand the waiter your Mondo card, and he swipes and authorises the transaction. At this point your Mondo account is deducted $90 (equivalent in GBP). The waiter returns your card, along with the receipt for your signature, and any tip you wish to add to the bill.
Because you’re a nice person, and the service and food was good, you tip your waiter - lets say 15%, which is $13.50 on a $90 check. So you add $13.50 to the receipt and sign and leave, as is the norm in the US. At some point the establishment will reprocess all these receipts and add on the tips. In your Mondo account, the $90 transaction becomes a $103.50 transaction, and as it has already been authorised, this drops you into an overdrawn state.
It would be good to get a notification if you go overdrawn. I only noticed by accident.