Deducted money for a closed account

Good afternoon I'm very unhappy with Mtn they are fast to take you're money but doing a reversal is something they don't know. I had 2 contracts of witch one ended and ben converted to prepaid, been billed and they took off a debit order for that non existing contract again. I've phoned 808 for a reversal on that amount that according to them takes 7 working days and after having to wait for there stupidity I've been told they can't tell me when I'll get it back and can maybe be credited for the amount. It's a load off nonsense i have to wait for something that shouldn't have happened in the first place. I'm not interested in being credited i want my money back asap. I'm stoping my debit order until i get my money back and won't be taken for a fool again, customer service is a joke honestly is like talking to brainless thing's that you have to telo them how to do there work. I want answer's not excuses