collection fees on clawback amount

I have a claw-back amount that was due to discovery and made a suitable monthly arrangement with the service provider to pay into their FNB a/c. i have been paying diligently up to my final 2 installments.

I wanted to clear these final installments at one go , only to find out that i was misinformed and the account had been handed over . so now im told i have collection fees to pay . to date discovery has been acknowledging my payments on the initial claw-back account

So can they take up the collection fees as its not my fault i was paying to their discovery account and not itcba a/c