Complaint FNB Credit Card Department

I have had enough of FNB’s non service I have some concerns but even when I log the complaint on FNB online banking where it states that someone will call me to resolve the issue within 48 hrs from the time I made the complaint, well that is not true at all, I did that last week Sunday, which means someone should have called me by Tuesday or Wednesday, but nothing. This was my complaint, FNB Credit Card Dept doesn’t help if you do not have FNB app, not acceptable I am a customer and the APP does not function on my phone, even consultants have tried. Consultants at the branches and credit card dept said I have 55 days to pay back any money I use without any interest. This is a blatant lie. I have used the CC twice Still get SMS that I owe a huge amount every month even after I have paid it back. I need someone to call me to discuss how we are going to resolve the issue. If I do not get a call after this I will after 40 years leave FNB and take 44 of my friends with me.