What am I supposed to do in this situation in school?

I have asked questions relating to this in the past but I have spoken about this.. I am 15 and I have been sexually harassed by this boy in my class for a while and I know who he says the exact same things too. So here is the situation I am now in at the moment. , I spoke to my year head/dean first thing this morning but I didn’t realise that he was going on a residential trip 10 mins later and won’t be back till wednesday evening, but when I told him he was as nice as he could possibly be and he asked me to speak to the vice principal who deals with these things about this situation as he couldn’t do anything about it at that time because he was leaving so soon. He then asked me to go and speak to him on thursday morning first thing about how I got on with talking to the vice principal, which I thought was very kind and helpful. I then went to the vice principal with my mate I told him about the messages,and showed them his reply being “he likes you”.. I was so angry because I know who else he has said this too and he could tell I was annoyed with him and all he could say then was I’ll call him up.. Which I was happy enough with. as this boy is in my class I know if he was to be called up and did he?? Nope he didn’t. What am I supposed to say to my year head on thursday, now I feel even more ashamed that I have spoke to someone who preferred to sit typing on his computer than to resolve a situation of one of his students, I’m so embarrassed and feel so guilty.The messages were about meeting him in disabled toilets in school to kiss, meeting outside toilets to hug and touch my backside that it would turn me on, and there’s been more he’s asked me very inappropriate questions about my boobs also. what should I say to my year head? Any ideas?