Unauthorized Nebula Charge Taken From My Monzo Account

I am writing regarding an unauthorized payment of £49.99 that was taken today from my Monzo account by As Nebulap. I did not approve or knowingly initiate this transaction and I have no information about any product, subscription, or specific service that this payment might be related to. Upon noticing the charge, I immediately blocked it via my Monzo account to prevent any further unauthorized payments. However, the £49.99 has already been taken, and I consider this an unapproved transaction. I am based in the UK and I request a full refund of the £49.99 to my Monzo account and confirmation that any related subscription or recurring payment has been cancelled so that no further charges are taken without my explicit consent.