Unknown Debit order

I bought a car which was financed by MFC, i started paying my first instalment in December 2018 and because i got paid earlier the debit order R5010.47 went through 14/12/2018 by the original payment date on the contract is 25th of each month. To my surprise today i received an sms and they debited the amount R1866.51 from my account and its not even my monthly instalment amount, When i checked on my online profile it shows that am in arrearsi went to their branch earlier today and spoke to x3 different people and they putted me through to Gugu at collections but i had to hold for more than 45min without any help, i need MFC to explain to me whats going on and why is that amount deducted and to please reverse it because its January and i need that amount for my kids school needs