Terrible experience

I missed the payment to the company last year october handed me over to debt collecters.Nimble said that the owe amount as of 2026 july was R1450 which i settled..fast forward to september i receive a message that my account is handed over for listing i owe them R6400.I ve been trying to get the company to resolve the issue with no luck they can even explain how they got to the said amount.Yoh i m so frustrated and dissapointed with this company .they just want to **** people of their money