Difficult to cancel, poor communication

I renewed my contract with them on 20 Dec 2019 for one year. On 1st March 2021 I send a email to cancellations instructing them to cancel my account and received a computer generated confirmation email from them. I phoned them and they confirmed receiving my cancellation. They took their payment end March 2021. On 2 April 2021 I send them another cancellation instruction. End April 2021 they took another payment. I then stopped the debit order to prevent them from getting another payment. On 6 may I wrote to their Debtors telling them that I have cancelled my account on two occasions and why do they still need a payment and they never rep****. On 12 May 2021 only did I receive a cancellation confirmation email from them. On 22 June 2021 I received a SMS from them telling me that they submitted me to the credit Bureaus if I don't pay the May account. So I get a bad credit score for an account that was already cancelled on the 1st of March 2021.