Capitec gives incorrect information

I took out a R500 personal loan about 2 weeks ago at Capitec Bank. I mean the first debit order is only on the 24th of this month. I paid R400 on the account yesterday and it still showed a R180 outstanding balance. When I wanted to settle that today, I saw an extra amount suddenly showing the R180 PLUS and EXTRA R327.57 called a settlement amount. What the heck? The guy who helped me at the branch never mentioned this after I asked his twice that I will settle the full account in a couple of weeks. How can this be allowed if you pay off your loan within weeks? This sounds ********** and I have heard of how many people have experienced this. Please explain the reasoning behind this as I need to take this up with an attorney.