Pending Overseas payment for Over four weeks

I normally receive deposits into my account from an Overseas vendor which can take between 3-9 days to reflect. I started following up when the payment didn't reflect after 12 days. I've been to bank branches, I've been referred to contact centres and no one has seemed to be able to assist me. I'm constantly referred to another phone line which ends up being a failed attempt as they refer the call. it's a constant unnecessary chain of unresolved calls. This is really *********** in my view. How can a stream of divisions not know where the funds are or to trace them?