I keep getting calls on my iPhone from a firm in Sheffield, about my energy supply. At least one call a day for over a week. I blocked this caller but am still messages from this phone number left on my answer phone! How come?
Tap onto the blue i within a circle that's next to the caller time, scroll to the bottom of information and the option to block that caller is at the bottom. It will ask you again in red if you want to block the contact, tap and it's done.