There are apps for the iPhone you can get that block both calls and texts, Mr Number is one of them. The only problem -- at least with the android version that I used, I don't know if the iPhone one is quite the same -- is that for about half a second they can still call you before it cuts in and automatically ends the call, but it's better than nothing. The only other alternative that I found was changing my number which was done free of charge when my mother rang up my provider twice saying that she'd take it to the police or just cancel my contract and get a pay as you go sim if they did nothing about it. My situation was a little different though, it was a bit more serious and a lot more emotional than that so you might not want to go to such a drastic measure.