i have gotten itt 2 they yell at me like crazy wtf

I am sick and tired of this idiot calling at odd hours,The thing is at the phone starts with 5 then the area code I guess.Anyway when the call its a foreign person and they are yelling at me,no clue what language but I AM SICK OF IT!!!! When I try to call the number back it says that the number is out of service,what do I have to do??? change my phone number again?????