Debited twice in a month on wrong account costing me bank charges and damage on my credit profile

I am so ****ed right now I changed my debit account on 28 August to a new account on 20 September they still deducted on my old account costing me bank charges for unpaid debit order and damaging my credit profile for having unnecessary unpaids kn my name, on 21st seeing that they have not debited i went into their WhatsApp chat i paid the amount owing but still on the 26 September got deducted again i am busy trying their line no agent to speak to keep listen to the robot voice you better sort this out urgently and i no longer wish to pay bia debit order i will transfer myself since you seem to have problem in debiting