Unpaid Debit Order

I have a cheque account with Fnb,a product that does not have credit facilities. Three debit orders were due on my account yesterday 27 December 2017. A R1000 direct transfer was made from an Fnb account at around 21:17 in the evening.I even received confirmation that the transaction was successful also checked my cellphone banking and funds were reflecting. This morning I received notification that all 3 debit orders were off. I was R14 in the red and I adjusted immediately by transfer to bring my account into a credit balance. Around 08:40 I then received two notifications that two debit orders were returned.Having called the call centre I was advised that the R1000 transaction only cleared this morning.Sabelo(client services)& Ivan(supervisor) advised that deposits Fnb to Fnb can take up to 24 hours to reflect. My question is how come when I checked my balance it reflected as available then now debit orders are unpaid. How is it that my bank can clearly see that I ensured that my debit orders are covered sufficiently yet by some banking technicality I am disadvantaged by having to pay unpaid fees. I need my bank to help me reverse the two unpaid fees of R100 each as I cannot afford these and also ensure that the 2 reversed debit orders are paid. Is it too much to ask for? taking into account that I made means to make sure that my account had sufficient funds before midnight. Dissatisfied client