It isn’t for Monzo to check at first, it is for you HR department to check. If the money has not arrived, it technically isn’t your money yet (even though you are owed it) as it hasn’t arrived and isn’t with Monzo.
After contacting your HR department to investigate, and they are adamant that it has reached Monzo. For Monzo to do any check, they will need a Transaction Reference Number (TRN) from the BACs/Faster payment transfer which only your HR department’s bank could provide. Get that detail when you call your HR department so Monzo can back trace the transaction.
Always contact your own work if pay does not arrive!
Oh, and Monzo’s contact details are on the back of your card.
0800 8021 281
help@monzo.com