Monzo should refund this straight away and go through the chargeback process to claim the money from the merchant.
I had something similar happen a couple of years ago (albeit with a UK retailer rather than Uber).
A word of caution - there’s possibly a risk that a chargeback may be found against you and the money subsequently taken back by Monzo. This happened to me and I captured it here:
I can therefore recommend - just in case - pulling together anything that may support a future dispute with Monzo, such as being able to justify your location when the transactions were made (e.g. a receipt from a shop, a work mileage claim…)
I’m sure you’ll be fine, but worth being on the front foot 