Disappointing Service from MTN South Africa

I am very dissapointed with MTN in terms of handling queries. Not only is it difficult to speak to someone on the 135 number. I have paid an account for my deceased husband contract and to get a paid up letter from MTN is very difficult or rather will not get one. I have been requested the letter as part of the estate finalisation and have emailed billing, customer care service, retention department and the legal department but without any help from the department. I only got an acknowlegement email from the legal dept. I have been requesting the letter and for a month with not response. Its very disapointing for such a big company not to care or assist their customers. I am very disappointed, angry and a disatisfied customer.