Deliberate ******* customer service

I app**** for a contract in October, which I cancelled a week later as I didn’t want it anymore. The phone arrived in January, after I had repeatedly called MTN and Mondo and I was advised that it had been cancelled. I returned the phone shortly after I had received it and contacted both MTN and Mondo but I received an invoice this week. I have emailed countless times and not a single person has contacted me. Instead I keep getting invoices and reminders of a debit order. I am beyond livid at the incompetence and blatant ignoring of my emails from MTN and Mondo. I need someone to call me ASAP and not to get debited AGAIN because that will make me lose my mind completely! I’ve spoken to countless people that have not been assisting me. Last week I finally spoke to someone with abit of sense, who said to me he was being a manager. Minenhle Buthelezi. He assured me on Friday the 11th that I would have my refund this week. I now receive an email that I must contact MTN for my refund. Utter bullocks! I’m not wasting another penny on airtime to call useless call centres. I want someone with a sense of urgency, and competency to sort my query out and I better have my refund