FNB not Honouring what is in the Home Loan Quote

I am in the process of transferring my home loan from Nedbank to FNB. FNB quoted me an insurance premium of R444.86 on the quote that I signed (***). When I called FNB on the 26th of November 2024 to take the insurance, this value changed to R471.92 (P***), after a long negotiation as it was initially very high. When I went to the lawyers to sign, they advised me that FNB must honor everything that is in the quote including the insurance premium. Please lower the insurance R444.86 as it was stated on the quote. I am really wondering why FNB did not honor what is in the quote in the first place.