Unnessecary Delays

I disputed 3 debit orders that went off my account more then 40 days ago. To date I have not received my refund. Exactly how long must I wait for monies that were not supposed to go off my account, for my refund? I find the delays by FNB to be inconvenient. It might not be alot of money for them but it is for me. I urgently await feedback