Poor financial administration

I am a customer that always ensure that my payments are made without any problems and timeously. However, I did make a mistake with the payment of my February account. Once this was brought to my attention I rectified it and the outstanding payment was made on 13 March 2015. Now, I receive an SMS that I still owe outstanding money. I do not think I should be liable for the R50 administration fee every month because of poor administration.