Cancellation of account impossible

My mother passed away in October last year. I have tried without success to cancel her telkom account since then. Yesterday I received yet another account for rental for her account. I have emailed telkom on numerous occassions, hva ebeen twice to the telkom branch in my area who tried to do the same and have phoned the call centre now on two occassions whose staff have sent requests for cancellations on my behalf. I have provided all necessary dsocumentation over and over again, the matter has supposedly been escalated on at least three occasssions, all to no avail. What am I supposed to do?