Brooks Luyt attorneys client FNB is adamant not to change their mind, I am told

Brook and Luyt office called me last week with regard to my FNB smart account. I was told the bank (client) is a adamant in their decision debiting R4637.45 of my account even though I explained to FNB agent (Brooks & Luyt attorneys) that the settlement given to me by the attorneys office was R1950 just after the 19/01/2018. I further cited that to the so called investigator from Brooks & Luyt that after I called the office on the 26/01 Francinah (attorneys-call center supervisor) confirmed the settlement of R1950. Ten-fifteen minutes later she called and mentioned that their client (FNB) changed settlement offer on the 25/01, previous day. What does not add up to me is:" how come the attorneys office did not mention to their client (Bank) on that I promised to call back before month-end of January, which I did, to confirm the payment of the agreed to settlement." On January 26 when I called back I am told the Bank changed the settlement the previous day. "It was before month end people, where was the money going to come from. Why not further mentioned the agreement between me and attorneys office of making a call before month ending."

Please help, this is an unreasonable action by attorneys office.