UNSATISFACOTRY SERVICE - WRONGFULLY BILLED

In July my account was double billed after which I logged a complaint and was refunded and received an apology from MTN. My account is paid via debit order since I became a MTN customer about 20 years ago. Now I received a phone call and is advised that my account is in arrears with more than R600. I want to know how my account can be in arrears if I have a monthly debit order on the 15th of each month. I was advised to call customer care which I did. Customer care gave me an e-mail address to send my query to. The e-mail comes back undeliverable. I phone customer care again and they give the e-mail address again. It still comes back undeliverable. As a MTN client for such a long time, I expect better service and an answer to my query. Also about 2 months ago I wanted a quotation on what it would cost to terminate my service. I was given a head office number which I phoned and requested the relevant information. I was told that I will receive an e-mail with the necessary information. Too date I have not received any feedback. I also asked why my contract on my ****le has gone up twice of which one incident was explained, the other I am still awaiting feedback on.