Payment error

I am not happy at all

I made a payment on the fourth of July and the payment went out twice, there was a system error on their side and I've been calling to relort the matter but even today i haven't received my money. They were supposed to reverse the money back into my account but noo they are still doing an investigation....how can i a pay the same amount twice, at the same time...because the amount went twice and the time is the same,in minutes ans second.....Can you please reverse my money back into my account please i need it...