National Lottery nuisance

I'm not very impressed with getting calls 5 times a day telling me to push a button to play the power ball. I don't have time for nonsense and I would never waste my money on such garbage. This is from the National Lottery, how they got my number and why they're allowed to use it to harrass me, does this not contravene this latest POPI act? I've never played the lottery in my life, and this is a complete nuisance. Does anybody know how I can stop them phoning me? Every time I block their number they just use a new number next time