Harassment - Incorrect number loaded to their profile

If I could give this firm 0 stars I would. I have been harassed by this firm for over 3 months, with no response despite numerous calls and emails. They have my telephone number loaded against another individual. I receive on average 4 harassing phone calls and 5 SMS's on a daily basis. I have called them a total of 14 time, and emailed 7 times trying to get this sorted out. To no avail. I am also unable to block them, as they keep changing the SMS number, or hiding their telephone number. Has anyone had any luck in either getting these people off their backs or reporting them to relevant authorities?