http://webcazine.com/12731/how-to-block-all-calls-except-those-in-contact-list-on-galaxy-s5/

tried above but the screen I have is quite different and my version is 6.0.1   android.

I sick and tired of student loans, cruises, resorts, credit cards and car repair insurance, I had blocked 99 calls but that's the limit I can block. So now I'm getting several calls a day and they keep calling back.

Is there an app that will do what I want?