I had an account wit...

I had an account with SOS.. who merged with National Security. On 31 May 2021 I was in the advance stages of selling my property at which I had Security service through SOS.. I sent an e.mail to cancel my contract.. I was later contacted telephonically by Lynette whom I advised of the termination. She later responded to my mail stating that she did receive my cancellation letter as my account was subsequently cancelled. Now they are harassing me and sending demand for payment of the account.