As per my post in another thread, someone suggested making it a whole new topic. Please see https://community.monzo.com/t/a-message-from-natwest/2174/4?u=mikes
Basically, having the ability to insert notes against your balance for any transactions that you know have been made, but have perhaps have not gone through yet I.e. Offline transactions. This could physically reduce your balance. Then either the user be prompted when a payment for the same amount is received, or the note automatically be removed, therefore showing the correct balance.
These notes could be time limited to prompt within 4 days to see if still required.