Why does Vodacom keep trying to contact a deceased person

My father passed away last year Oktober, about a month after his passing we got contacted by vodacom asking to speak to him. After explaining to them and submitting death certificate they still have not stopped. I am on my own contract and i was called every 2 days, this year since the 2nd i have received calls every single day asking for my father, the more i explain to them the less they understand, in the morning between 08:00-08:10 i get a automated call that drops whenever i answer it, upon redialing the number its always vodacom. Then i block the number and around 15:00 i get another call this time someone speaking and asking for my father.

Thank you vodacom for the constant reminder of my loss, i guess getting a deceased person to go onto a contract again by phoning their relatives are a new market scheme. You are absolutely horrible and a menace to society

Kind regards Zack