Car track is a *******!!!!!!!!

What a **** of a company, I called them beginning of May to let them know that I am trading my car for a new one and I want to cancel my contract because the new car comes with a new tracker. They first told me they will call me. They never did for about 2 weeks. Then they start sending me messages that i am behind with payments. I tell them that I want to cancel the contract. They say I must pay R2900 for cancellation including May premium ( which is a *******). End of May they debit June premium long after I have paid for cancellation. They are a **** and rip people off!!!!!!!!!