If you are getting these calls to your cell phone you can go to your company's page online or go into the phone store and have them block the number so that the calls will not come thru anymore. You can also have them turn off "private" or "unknown" numbers so that those will not come through either. If it is a house phone, call the company and see if you are able to block numbers for that otherwise maybe you are able to unplug the phone line while sleeping.
Just a few things that may help :)