Is there a way to change my name in Australia?

I want to change my name .. this is because some people have been teasing my name , my name is denis and they say, if you change the d into a p it makes .. a human d**** ( I am not trying to be rude ) well, I find this very rude and annoying and they started laughing and laughing for ages.. and they never tease themselves.. so now I want to change my name to dennis .. so how can I do that? and I am under 18 years of age by the way.. and my parents won't let me change my name..so what can I do about this?