**** about the debit order

Cartrack **** to me about the amount I will be paying, fast forward to 10 months later I'm getting threatening emails and messages that they will take legal actions against me if I don't pay the R2600 I "refused" to pay. Refused?? How does this happen when cartrack is the one that debits money from my account? I was told I will be paying R145 a month not over R400. This is totally unacceptable, they knew I'd have never taken that package if they told me the correct amount so they decided to not say a word about about it untill 10 months later, so disappointed.