Plain And simple *******

I just have had a situation whereby I paid 2 full installments for my car in December 2018 and MFC without any notification, decided to restructure my payments and sent me a statement stating that I must also pay now in January 2019 I called the call center and spoke to Nokulunga Dube who said she will send a request for that restructuring to be nullified, indeed it has been reversed however the new statement has an amount of R91. 15 that is due to MFC which I refuse to pay as I made 2 full payments in December so that I won't have to make a payment now in January because I have other plans, how does MFC now charge me this 90odd rand, where is it coming from as I had paid IN FULL for December and January....this is **************** and I refuse to pay it....so annoyed.