Incorrect credit bureau update

I have a loan with old mutual and never missed a payment. I only made arrangements for 4 months to pay half the amount last year. This year I have been paying the full installments every month but on my credit profile they update it as missed payments and refusing to update it saying as long as I am in arrears of the arranged payments they cannot update it. I already paid the arrears. The sad part is that it affects my credit score and their update is not correct as I didnt .it's payments but was in arrears because of arrangement