Flabbergasted with ABSA

I have an Absa loan since 2008/9, paying more than half of the installment each month. When I enquire about the settlement balance in 2017, the call center told me it's R 16 000. Enquired again on 27/07/18 and now it's only R 13 000. Only receiving statements twice a year. How on earth is it possible to still be owning so much???????? While I was still banking with ABSA, every month there would be a debit order named Nadeo, never the same amount of money.... When I enquired about it, nobody could tell me what it is. Now I get a response, only from this site, after I gave all my details so they could have contacted me personally, that the ID I provided them with, is not on their system!!!!!!