Vodacom not accommodating disabled

We've been trying to cancel a contract registered under my deceased father's name since Sep 2018. The phone number is used by my disabled mother who has no other way of contacting us without the phone. We've sent through all required documents more than 6 times and still they claim documents is outstanding. The Sim card is disabled every so often due to "payments being in areas" even though we pay every month. I've been calling customer service every second day to confirm payment is received as it's a huge hassle to reactive the account but no one will assist without the death certificate which I've sent multiple time and I have the read receipts to confirm this. This is such a disappointment that they keep sending SMS's and calling with automated machines after we've told them over and over the lady is blind and can't use these services.