Harassment calls all times of the day

Every single day this company calls me and hangs up when i answer. i finally got an automated message when i called back and found out who it is. i contacted the whatsapp number and gave them my info and asked to be removed from their calling list, they confirmed that they cannot see that i have an account with them so they cannot remove my number. How the hell do i get on your list without an account? and why cant you remove me? i will spam every message board you have until you stop calling me. you just call, and hang up when i answer. you wake up my family in the mornings and bother us in the evenings when we have supper and you bother me during the day when i work.