Poor Service

Good Day

I just want to complain about poor services that i have recivied from FNB latetly, I cleared my loans back in 2016, I've also provided them with my paid up letters, Last year i took a Backup Pension Fund Loan, On the 29th of January i paid them R33.000 for the loan that i took last,When i try to apply for my new loan it was rejected due to the outstanding money that i was not even aware off. Now I'm asked to pay R1928.00 which i dont have a problem to pay so that i can be cleared fom risk category to zero, But my question is why was this amount missed back in 2016? and why did i qualify to get the loan?

I honestly love FNB with everything that i have hence i bought a house with them, I don't wanna leave fnb at all but if they continue to treat me like this i will switch banks.