@Rorie,
This isnt o2 Customer Services, so you will need to speak to customer services, on 0800 587 4007 or via live chat (via o2.co.uk/contactus if available) and hope they act in goodwill and refund it bac
Unfortunately, if the money was in the bank at the same time as your direct debit was due, then they will have just debited it as normal, as they wouldn't know the source of the funds..
- Xperia 1V - o2 and Spusu
- Pixel 8 Pro - o2 and Vodafone UK