Reversal of fund's

Fnb didn't get back to me concerning my complaint,my money just got lost without no one explaining why they couldn't reverse a transaction done through their application and immediately contact was made to the bank after the transfer..Am truly disappointed with their services,its very easy for fnb to debit your account when it favours them but not when the customer have a complaint,they automatically don't have the details of their client or how to reach them....its not a nice experience and it makes me wonder why I should still be a customer there...