Delayed payment reflection on my loan account

I have a Pension Backed Loan with FNB, for the past +-5 years I have been with them, they never update the payment on time. Two or three months passes by without the bank reflecting the payment. A deduction goes off on the 25th of every month, however, the actual deduction on my balance does not reflect. I must fight all the time. Please can someone do their job on time. My April payment is still not reflecting. The interest on my balance is incorrectly calculated.