Useless fnb premium *****ing up my account and now avoiding me cause they have no answers

I’ve been trying for the last 3 days to sort out my credit card account that fnb *****ed up. I keep calling in to the “premium” bankers ( not sure why they call it premium, it’s been consistently useless). Every person gets confused, can’t answer me and then tell me they will investigate and call me. No one has called me back and because there are no other numbers listed, like complaints, there is nothing I can do. The complaints form does not even work - not responsive so does not scale down for mobile devices so I can’t even log a complaint.