How do you get rid of a clingy person?

Okay so AGES ago I befriended this guy who is about 10 years older than me and was new to this country; anyway when I gave him my email and used my phone to help him figure out what his number was I thought he would only use it to ask about which places to sightsee although to be completely honest I thought nothing would come of it at all; one of those things where you just add people on facebook when you meet them but not really talking but it didn't turn out like that. Anyway he started getting really clingy and phoning/emailing/texting pretty much EVERY day just to ask how I was and what I was doing- and he would sometimes ask to meet up with me. After a week or two of this it freaked me out; especially when I tried to give him hints that it was getting too much; i would put off replying for ages but then he would contiue to reply. I then completely deleted everything of his a few weeks back and all was good and i thought he had got the message but recently he's started calling and texting just as persistently as before and adding me on my email even though I swear I clicked block and delete. How do I get rid of him/let him get the gist? Every time I think of telling him to piss off-it sounds really harsh and might lead to more texts