I always miss the phone call they never leave a message so when I try to call them back the operator says it's a non-working number it's a bit strange to me
Don't answer.If you have a smartphone or other mobile android device, go to google play and download a free app that will block that number and any others that you do not want. For a landline, most carriers have a blocking feature( i have at&t)-may cost a few dollars-and you can also purchase a caller id( also availble through phone carrier for nominal fee or in a phone package bundle) at any department or electronics store-which are relatively inexpensive( $15 @walmart). This should afford you some peace of mind, and each unwanted number can be added to blocked list as needed.Good luck.