STop texing me already please ?

this kid is obsessed with me. he is kinda my friend . he really likes me and has asked me out over 3 times . i don't like him like that. Anyways he got my cel # from my friend . ANd he wont stop texing me . i hate it. and any questions he send me and i don't answer he will ask it till i do :S what do i do. texing cost money on my phone and it's annoying me . i told him my text cost $$ bwe he keeps texinggg. i only text my bffls some friends and my bf .