I have statred to use one called WideProtect. Not sure if its on the Goople store for android phones.
This allows me to block numbers using a wildcard entry. For Example I can block numbers that start with 09 525
It also does not require a constant internet connection as some apps require this to check the number against an overseas database of spam numbers. It also allows me to block text message but I havent used this side of it yet.
You should also be able to call Vodafone with these numbers so they can follow up and investigate them.
Thats what I did several months ago. Then I got the WideProtect app on my iPhone and havent been bothered since