A direct debit is a contractual agreement, they have zero access to the bank account, just the unique identification number and an automated system that requests money from that unique identifier once per month.
And that if there's no money in the account, they don't take you into credit, but instead just pause service until you pay
That's literally impossible, it's not how it works
At the very least it's literally impossible in UK and EU.
The system isn't actually taking any money from you at all, it's merely sending requests to the bank to ask for the money.
Some banks automatically will go "okay!", some need human confirmation for every transaction, ALL need human confirmation for any transactions over £200 (by law)