Hathway - Stop Incoming Calls from Hathway on my Phone No

I subscribed for a Hathway broadband connection in September ****. It was a very bad connection and I was so irritated by their endless phone calls that I stopped the service. It has been two years since I stopped Hathway. But their phone calls did not stop. I have been still receiving calls continuously. This has reached the level of harassment. I want Hathway to delete my phone number from their records so that no customer care executive calls me again. I do not have evidence as such. But I can mention the last number from which I received the call today. **********.