FInchoice and Nimble group

I app**** a loan from finchoice(Crediworx) i really regret to take a loan there, this is really a company that is quick to call you when you skip your loan payment. So what happen they handed over my account with Nimble group which i didnt have a problem, when nimble group call me and do the arrangements with me opted the option to settle my account so they made the debit order and i also made the manual payment because i change my banking.So what happen i overpaid my finchoice account because their debit order were late to debit so i decided to do EFT payment and after i have done with EFT payment and debit order took place afterwards. So i phone them Nimble group that there is double payment and i am requesting for refund. They advice me to write a letter,and also attached copy of ID, bank statements. I did all of that. So what suprise me when i call nimble group to so rhe follow up they rather tell me they still waiting for finchoice to respond if i still owe them. I really do not understand this when i call fonchoice they will tell me my account is with Nimble group is not longer with them. So both companies they do not give a clear answer. I really regret this