I joined cartrack Ju...

I joined cartrack July 2025 for their service to save guard my car, the contractual agreement was supposed to be R209,00 per month, which I didn't have a problem with R209,00 per month, since I joined cartrack, they've been debiting R120,00 per month, I called them and asked why are they debiting R120,00 instead of R209,00 as per the agreement, I was told the device that I wanted isn't yet active on the car,that's why they don't debit full amount, on the 22 December 2025, I received email from Cartrack claiming that I owe them R414 of the difference they didn't debit from July 2025, please advice me what should I do