Query not answered to my satisfaction

I am on Edgars account holder from 1985 and have not defaulted on payments on my 6 month interest free account. However in December 2014, the billing which normally arrived via post was not delivered as a result of the postal strike. As a result I inadvertently shortpaid for December, January and March. By this time an overdue amount was accruing interest and late payment charges. When I called to query in March after receiving calls on my cellphone, I conceded that I was in fact in arrears and by April made certain I paid what I was told the final amount was in order not to incur further interest or late charges. I also requested that my statements from January be mailed to me to prevent such a situation from recurring. <br> <br> Subsequently, I found that my May statement had a late charge of R44,33 added to it and on inquiry was spoken to very rudely by Andile who was adamant that this amount had been added on for half the month since I paid the payment owing in full on the 15th of the month.<br> Her supervisor a Mrs Sibiy re-ieterated this point adding that this was charged for the March shortfall.<br> How is this possible since the April statement did not reflect thiS?