Disgusted by MTN and their shocking service and lack of client care

Very unhappy with MTN. I have been a client for years and have never had an issue with billing. January they double debited my account even though I have a debit order and have never missed a payment EVER. I have emailed and called and to date have been ignored. My complaint goes unassisted and essentially what MTN have done is ****** money out of my bank account. I do not owe MTN this money and I want someone to correct this. I want to be refunded and then I wish to cancel the debit order so I can pay by EFT as I no longer trust MTN. As soon as I can, I will move my business to another service provider. It makes no sense that I get treated this way after being a loyal and faithful client for so many years.