082145 harrasment

My contract is due for an upgrade however I have no intention of upgrading it. I get about 5 calls from 082145 per week offering me an upgrade on both of me phones, That's 10 phone calls per week on average. On answering the phone some terrible hold music is played for you for about 20 seconds before the marketer from "head office" answers to offer you an upgrade. Each time I have answered this call I have informed them that I don't want an upgrade and please stop calling me. They keep calling. If I don't answer then they just call right back. I blocked 082145 only to get called from 082140. It gotten to the point where if I don't answer my cell phone then they phone the work phone. I cant wait to leave cell c as this is harassment and their service is in general pretty C**p. Oh cell C Vodacom called. They say Hi and thanks for the customer.