Ridiculousness

I am deeply offended by FNB and their recent conduct with my accounts. I took 2 phones from their Devices division on the 25th of february 2016. i realised my account kept going into negative due to an early debit date and i called them to resolve it. The agent that assisted me said they could not change the dates because the system wouldnt let them. I called in twice more and they finally made it work, but guess what they only moved the one device and left the other. It carried on with 2 different debit dates until now an answer was never provided why. My credit rating as messed up thanks to FNB.......Great service to the nation. I received a call in October after i emailed FNB and i was told everything will be resolved but guess what they had put 90% interest on the device. I receive a call from them with lawyer threats from on of their managers(Overbearing arrogant individual, the bank itself personified) who refused to explain to me but chose to patronize me........I have been offended my problem hasnt been solved and guess what I still have to pay a ridiculous interest..........No none can pull a record of "recorded conversation" i have had with them previously???