Loan Not Decreasing

I have just got off a call with NDS Credit and they have said an account that was sitting in R2000.00 plus range owing is now R3796.00. And they cannot pick up my last payment. I was dealing with another legal company on paying my account but later received a sms of demand from another company. I have requested that Woolworth's takes this account back as i cannot deal with the constant change of legal companies as this always makes my account increase. it also effects me as i have to constantly be sending proof of payments to these companies. This is the 2nd legal company in 3 months and i have been paying the amount agreed upon. I want to increase it to settle , but how do i know that will work. Woolworth's needs to contact me and resolve this as i cannot be paying for a yea and still on the same amount that i was at the beginning of the year. I suggest Woolworth's updates NDS immediately.