Refund not happening

This is not the first time FNB does this.. On the 22nd of August, they debited my account. On the 25th of August, they double debited my account again for the exact same thing. On the 27th of August, i logged my first request. It took me 5calls. Since then I have called and followed up 31st of August/ 4th of September/ 9th of September/ 10th of September and I've logged 3 complaints. How does it take my own bank 3 weeks to refund me money that they were so quick to take? When an agent calls me back they let the phone ring twice and hang up. Seriously pathetic and extremely disappointing to keep hearing an urgent refund and 3 to 7 days. Its been 3 weeks now!