FNB FUNDS DISSAPEARANCE

I am really disappointed with the service and so called investigation outcomes How can FNB say they can't trace payment when the amount is reflected on the my bank statement but not available? I still repeat why must the matter be taken up with the paying bank as the amount left my account? really this microwaved or scripted solutions I am receiving from FNB is something else, I mean such a big and reputable bank providing such minimal service to its customers