In need of paidup letter

Good day I have 2 account with nimble group 1 is wonga and 2 Russell's.so I settled wonga account when I ask for paid up letter they tell me I still have R163.94 which I know nothing about no1 is making that clear how come I still have balance while I settled the amount.i don't know really as they keep on saying they'll escalate and 1 of there consultants will call me it's been 2 days now.