Stop billing me for services cancelled on 1 April 2020

I am absolutely shocked and appalled by the level of service received from you. I gave notice to cancel my contract on 2 March 2020. On 1 April 2020 I received email confirmation from Supersonic that the services were cancelled. Up until today however, I am still being billed. From April I have been calling and emailing and whatsapping asking for you to stop billing. Your systems does not even seem to indicate that I cancelled my services as I keep having to explain to your people when I cancelled and when I received confirmation that my services were cancelled. Your people keep asking me if money is being deducted from my account, and whether money is being deducted is irrelevant. You keep raising invoices for services not rendered, and if I don't pay, certainly you will hand the account over to debt collectors. I even received an email about my account being in arrears, but explained to the woman what happened, but no response. The email address was *** and I used case ref: cas-113706-xos1y3. Please in heavens name stop billing and send me an updated account statement indicating the reversal of the ridiculous invoices raised for services I never received and were confirmed cancelled. Just stop being so ***********. It is frustrating and annoying and I could end up with a bad credit record because of you.