MTN refuses to cancel deceased father's contract and refund money owed

Dear MTN. My father passed away in December 2017 and my mother has been struggling to cancel his cellphone and laptop contract ever since. She has been to the MTN Oakfield branch numerous times and she has made countless phone calls (including to the legal department). The debit order kept going for months after my mother notified MTN of his passing (adding up in thousands of Rands being wrongfully deducted from his account). To add insult to injury, his account was even charged with a R3 742.98 fine for supposed breach of contract! Please explain to me how a deceased person can be in breach of contract? In addition, my mother has had to resubmit the required documentation (death certificate etc.) numerous times after various staff members at the MTN Oakfield branch resigned and allegedly "threw away" the documents. My mother's number has even been blocked recently! The staff at MTN Oakfield should honestly be ashamed of themselves for making this process so difficult and frustrating for my mother. Please resolve this matter urgently - this frustrating process has gone on long enough now. I will continue to post on social media, Hello Peter etc. and we will not hesitate to seek legal action if necessary