If you can say which four companies you’ve tried, there might be others on the forum with experience of them who could advise. It will depend entirely on the systems in place at the organisation.
You could possibly cancel the old direct debit on your other bank’s website, and setup a new one online on the organisation’s website. But it depends on what they (the organisation who will take the debit) offer.
Also, Monzo will eventually offer the Current Account Switching Service, so you could hold fire until this is available, and it will all be done for you.
I’m currently sitting in a queue listening to holding music while trying to change my mortgage Direct Debit. I’ve done the 9 or 10 easy online ones, now I’m onto the ‘annoying list’.
Just tried to update my Congestion Charge Card details. Oddly enough I was able to add my Monzo card details to my account, however I was unable to do likewise for Autopay, which is what I use it for.
Got a notification that £0.00 had been taken by TFL, so they clearly support the card. Just not when using it for Autopay.
By way of an update, I called TFL with a query regarding the DD mandate form, and they actioned the DD mandate over the phone. All appears to have gone through swimmingly.
Also changed my TV License successfully ages ago (14 Sept) on their website - wonder if something’s changed? I used to pay by card manually, so Monzo CA was my first DD with them.