Viljoen & Cartrack frustration

They do not answer my emails, I'm trying to sort out an Cartack account of a car I sold over a year ago. I cancelled the cartrack thereafter. Now Viljoen Attorneys sent a threatening letter and threatening WA messages even after I requested by email from Viljoen attorneys details on the amount in arrears. Frustrating! You cannot call their number displayed on their website, if you do, Cartrack answers the phone!!!