Unprofessional and Unreliable Service

My car tracker account was listed at Nimble Group which I owed R1500 and was handed to them as R5000, they kept on pestering me with calls and they offered me a 30% discount and I agreed to it on a 3 months installment. They debited the 1st installment in January 2024, and I asked them on the 26th January 2024 for a settlement and they send it to me to my surprise it can't open. I made payment the same day on the 26 January 2024 for the amount that they provided. I contacted them on the 29th January 2024 for a paid up letter and I was promised it will be send to me email which it was not sent. I phoned later and I was advise that I owe R378 on the account when I asked how? The lady dropped the phone on my ears. I have never come across with such unprofessional service. I'm really disappointed in this Company!!!!