Severe harrassment about my dead father

I keep getting debt collectors and attorneys demanding money from my father, who has been dead for almost 3 years. The money that Standard Bank wants is a credit card fee, added after he died, and after I informed Standard Bank several times that he is dead. I've phoned Standard Bank call centre over and over again, I've e-mailed the dreadfully named "deceasedrecoveries", sent the documents, his death certificate, letter of executorship.... and NOTHING!!! I still get phonecalls from attorneys and debt collectors. Short of calling a seance, I can't think of anything further to do. My dad is dead is not coming back. ARE YOU LISTENING STANDARD BANK??? CAN SOMEBODY PLEASE SOLVE THIS ONCE AND FOR ALL!! And please, take a tip from the banks in the UK. They don't call it "deceasedrecoveries" - how tasteless and crass. They call it Bereavement Assistance.