Threatening dead man with legal action!

My father passed away on 16 June 2021. My brother went to your Woodlands outlet and handed over his death certficate and cancelled the line as my mother moved out of the house to another province and never used the phone again. Yet after several attempts and having to deal with your legal threats, final demands, constant sms's to my mother's cellphone!!!!!! we keep on sending copies of my late father's death certificate. MY FATHER IS NO LONGER ALIVE. YOUR CONSTANT LEGAL THREATS IS AFFACTING MY MOTHER'S HEALTH. WE ARE GOING TO INSTITUTE LEGAL ACTION FOR PAIN AND SUFFERING AGAINST YOU!! DO YOUR WORK!!!!! AND CANCELL THE SERVICE NOW. YOU ARE SUCH A DISGRACE!!!!! THE ACCOUNT NUMBER IS ***. I my mother receives another sms or another legal threat from you, there will be big trouble. I am waiting for your call on *** to tell me that you have sorted this out. It is click click and if you don't know how to do it, or you are just too lacy or just dont care, call me I will do it.