Refund my money now

I am so sick of these people you never get any assistance whether you call or WhatsApp them there is no response at all. I paid for my home internet on the 1st of December through the MTN App as it also allowed me to pay earlier. Normally they deduct on the 4th. But today I got a notification that they took the same amount even though I have paid already. I need my money back now. I can't wait to cancel this stupid contract. Poor service horrible customer service. REFUND MY MONEY MTN