LOST MONEY

I have requested a withdrawal from an international trading company. This company has released the funds but I have not received anything from them as yet. I contacted them and they sent me an ARN number for my bank to trace the money from their side and release it. I contacted FNB online and not once, but three times I was turned away because the service agent I was online with, did not know what to do with the ARN number. I tried to phone and was told I should change my card details with the company. I was instructed to go into a branch to do this, but what cer*****y do I have that when I make all the effort of going there that anyone will know what to do. I'm really disappointed that no one can help me, this is not the type of service that I pay for. How is it that a bank does not know how to use international ARN numbers?