Unhappy client

I lost my job few years back and informed Netstar about it then told them to close my account, they insisted to do so instead told there's an amount I have to pay first worth -R2000. I agreed to pay at least R150 per month to ensure that this amount is fully paid until recently when R400 is left i received an email stating that I have been using the wrong reference No that they gave me and i now have to pay R4299 of which I have no clue about. I then stopped paying a month ago and waited for their call to rectify this mistake instead they've sent my details to attoneys.This company is a **** I wouldn't advice anyone to be involved with it rather go for a different car tracker.