Cartrack sales harassment

Cartrack has contracted a call-center whose people have been harassing me continuously in and out of business hours. Even though I've blocked through the Truecaller application more than ten phone numbers from Cartrack's callcenter partner, they just continue their relentless strategy of recycling phone numbers which they use to call. A company like Cartrack will never ever receive my business for displaying its desperation for client subscriptions in this manner. How is it that their Marketing department cannot figure this out from the data?