Some additional info from the citizens advice website:
It says you can ask the card issuer to stop via phone, email or letter!
Stopping a card payment
The law says you can withdraw your consent and stop a future payment under a continuous payment authority at any time up to the end of business on the day before the payment is due.
To withdraw consent, simply tell whoever issued your card (the bank, building society or credit card company) that you don’t want the payment to be made. You can tell the card issuer by phone, email or letter.
Your card issuer has no right to insist that you ask the company taking the payment first. They have to stop the payments if you ask them to.
If you ask to stop a payment, the card issuer should investigate each case on its own merit. They should not apply a blanket policy of refusing to refund payments taken when the client gave their account number out.
You should point out to the card issuer that they should follow the Financial Conduct Authority (FCA) guidance on unauthorised payments from your account.