ADT Threats after service cancelation

I am now being threatened by adt due to my "account" which is in arrears, I cancelled with them in November 2022, they refuse to send cancellation forms after phoning them and logging complaints on their website requesting the forms since November. The last complaint logged with Hello Peter adt was going to contact me and to date no one has bothered... absolute pathetic company and clearly they are out to ***** people...