Unreliable, *************, lack of urgency

I recently settled and cancelled my cellphone contract with Cell C , but the still proceeded to debit me even though I was not owing them anymore as I had paid both commitment and current account amount. Now it's a hassle to refund me and I have been spending alot of money on calling them and asking for feedback with my case. The way Cellc is handling this is the reason why I would be hesitant to ever do business with them again.