Legal department - waste of time

My mother has passed away and had a contract with Vodacom. I have notified Vodacom that I would like to take over the contract and not claim from the estate. However they submitted the claim against the estate and is not responding to any of my emails and according to their call line, the legal department doesnt even have a number to contact them on. I have to sit around and wait for them to eventually get back to me. I have sent 14 emails over a period of a month and no response. The stores is also not able to assist me until they get the go ahead from the legal department. HOW LONG DOES IT TAKE TO RESPOND TO AN EMAIL OR RETURN A CALL? Their service is apauling.