Misled by home loan shortfalls division

I app**** for a Shortfall Loan when selling my house. FNB approved a loan of about R179 914.81 @zero rate over 60months where I had to pay a fixed instalment of R2 998.58. House registered on the buyer on 11 March 2025, the home loan so the shortall was R134 000 upon registration. FNB did not immediately close the home loan I was then debited R14 409.40 on the 25th of March where an interest of over R6400 was charged yet I was advised I won’t pay any interest. When I noticed this I called Mpinane Mokoatsi who was allocated to this case and she assured me that the interest charged after the house registered on the buyer will be reversed and go towards reducing shortfall loan when FNB eventually opens that shortfall account and a new debit instalment will be calculated accordingly. With this information I was expecting my shortfall loan balance to be R119 590.60 (R134 000 – R14 409.40) . I see FNB has finally opened shortfall loan account today BUT interest charged in March was not reversed so it did not go towards the reducing the shortfall as communicated so instead of having a shortfall balance of R119 590.60 I have a loan balance of R126 785 and in addition to that instead of paying R2 998.58 on the 25th, FNB kept the instalment at R14 409.40 how will I be able to afford this payment when I no longer receive rent from that property and have to pay rent where I’m currently based? Why did FNB make me sign all those documents if they knew they were not going to honour agreement.