**** service or lies

I had an arrangement with MFC to pay my account on the 15 May 2021 as it had an arrears, my statement showed an arrears of R 6 634 on the 10 May, i paid this arrears as per the agreement with the collections department, but another collectign agency phone me today to say there was another R 512 added to my account. Can this be clarified to me by mfc as i really dont understand this