No response from Investec

I have been trying to sell my MTN shares held by Investec for almost a month now and when every i call their call centre either nobody picks up, i get up on hold forever or when i do get through they tell me they will send me an email on how to register and trade online which they never do. Even the emails I have sent them have gone unanswered. Their service sucks and they don't even have the decency to respond to their investors.