Harassed by collections department when I don't even have an account with you

I am receiving up to 14 calls a day from your collections department looking for someone named Mr Kandasamy. I have explained over and over again that this is not his number, you have been given an incorrect number and to please please stop calling as I don't know who this person is. Your call centre agents just put the phone down on me and refuse to listen to me or transfer me to someone who can assist. This is harassment.