FNB is stilling from they customers

On the 25 October 2019 I take out a personal loan by FNB to do some revamp on my house. The lady at FNB help me to get everything ready for a personal loan but before i can get the loan at FNB i need to settle all my accounts be for i will get the loan of R85 000. I only received the question the next day on the 26 October 2019 before i can phone the bank and said that they made a dubbel payment on two of my accounts on Mass build is a builderwarehouse account and CTM thet paid in my Mass build R1662 and R14200. it was to late because the bank already pay the account and the account that i recieved was only R58 000 because of the settlement on my accounts. Whenever i ask for the proof of payment the bank said they'll send it but i never received the proof. So i decided to phone my one account holder RCS Mass build ( builderwarehouse) to find out it they received of a amount of R1661 and R14200 they said no. Only the R1661 so i went back to the back and asked again for a proof of payment and again they said they will send. After that i fight with FNB they send the proof of payment and there is were i saw that the R14200 is paid into a different account not mine. So i phone the bank again and they said i need to phone Mass build it is not there probeer it is mine when i phone mass build RCS they said the bank made the fault the bank must sort it out. I'm struggling fot two weeks and not one of them is will to sort out the fault not even the FNB the bank that made the mistake is will to help me.