Fnb is non-responsive

Last week I reviewed my experience with fnb and I received an email indicating that my complaint has been escalated and got a reference number. On Tuesday I received another email asking about the details which I provided. That was the last time I received communication from fnb. They have not even assured me that they are investigating. Just no communication. The situation hasn't changed. I don't know who to turn to now. This is bad banking practice.