FNB Credit Card - Missing Payments

Need assistance please. We have a business credit card with FNB. Last year November our credit card was put on hold, apparently due to outstanding payments. This year January 2020 we received a phone call to say we are handed over. Just like that. We got all our bank statements and has prove of payments. Some debit orders did not go through just went out and back in. I said to the collection department we do not have access to any FNB systems and cannot tell why a debit order can reverse back immediately. Only they will know. Every time I phoned to sort it our or to get to the bottom of where all the payments disappeared I get put through from the one department to the other. We getting nowhere with FNB credit card division nor collection department. On Monday the 29th of July 2020 a lady from collection department contacted me to ask again for payment. Again I explained everything to her of what happened and it was mentioned she will logged an enquiry with Admin to investigate the matter. Up until now no further feedback received again. It feel we were unfairly handed over and not sure what happened with all the payments. What can we do in this case? At the moment we are very unhappy for not getting any service from FNB.