Harassment via sms and calls

Sadly they dbt deserve a rating but unfortunately the site dbt allow me to give them minus. Aftr 2years they are back harassing me wth messages and calls for outstanding debt of another person that used my cell number. Called them and asked them to remove my number numerous times but still they dont. Was told rather to ignore calls and messages. Really now every 2nd day is really not on. Numerous affidavits and ID proof was sent but still they continue. I think I should get my lawyer involved now