Deceased contract holder

My 91year old father, who had a small airtime only Vodacom contract, died in Dec 2018. Certified copies of death certificate, id document and the required Death notification form were sent to ********** in Dec, Jan, Feb and March. His cheque account was frozen in Dec 2018 and all debit orders refused. He has no substantial assets, nor will. Now April 2019, STILL, Vodacom have not cancelled his contract, nor responded/acknowledged any of my eMail messages.